import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.StringTokenizer;

/**
 * @author Andrei Chugunov
 */
public class B {
    BufferedReader br;
    PrintWriter out;
    StringTokenizer st;

    void solve() throws IOException {
        long a = nextLong();
        long b = nextLong();
        long result = 1;

        if (b - a > 10) {
                System.out.println(0);
        } else {
            for (long i = a + 1; i <= b; i++) {
                result = result * (i%10)%10;
            }
            System.out.println(result);
        }
    }

    B() throws IOException {
        br = new BufferedReader(new InputStreamReader(System.in));
        out = new PrintWriter(System.out);
        solve();
        out.close();
    }

    public static void main(String[] args) throws IOException {
        new B();
    }

    String nextToken() {
        while (st == null || !st.hasMoreTokens()) {
            try {
                st = new StringTokenizer(br.readLine());
            } catch (Exception e) {
                return null;
            }
        }
        return st.nextToken();
    }

    String nextString() throws IOException {
        return br.readLine();
    }

    int nextInt() throws IOException {
        return Integer.parseInt(nextToken());
    }

    long nextLong() throws IOException {
        return Long.parseLong(nextToken());
    }

    double nextDouble() throws IOException {
        return Double.parseDouble(nextToken());
    }
}

import java.util.Scanner;
public class code{
    public static void main(String args[]){
      Scanner sc=new Scanner(System.in);
      String a=sc.next();
      String b=sc.next();
      int count=0;
      if(a.length()==b.length())
      {
      for(int i=0;i<a.length()-1;i++){
          if(a.charAt(i)!=b.charAt(i))
          count=1;
      }
      if(count==1)
      System.out.println(0);
      else{
          String s1=""+a.charAt(a.length()-1);
           String s2=""+b.charAt(b.length()-1);
          int a1=Integer.parseInt(s1);
          int b1=Integer.parseInt(s2);
          int c=1;
          for(int i=b1;i>a1;i--)
          c=c*i;
          c=c%10;
          System.out.println(c);
      }
    }
    else
    System.out.println(0);
    }
}

import java.util.*;

public class TheEternalImmortality
{
	public static long boufing(long a, long b)
	{
		if(a==b)
			return 1;
		if(a%10==0 && b%10==0)
			return 0;
		ArrayList<Long> ar = new ArrayList<Long>();
		if(a<b)
		{
			for(long i = b; i>a; i--)
			{
				if(i%10==0)
					return 0;
				ar.add(i%10);

			}
		}
		else
		{
			for(long i=a; i>b; i--)
			{
				if(i%10==0)
					return 0;
				ar.add(i%10);
			}
		}
		long total = ar.get(0);
		for(long i=1; i<(long)Math.abs(a-b); i++)
		{
			total*=ar.get((int)i);
			if(total%10==0)
				return 0;
			if(total > 10)
			{
				total = total%10;
			}
		}
		return total%10;

	}
	public static void main(String[] args)
	{
		Scanner scan = new Scanner(System.in);
		long a= scan.nextLong();
		long b = scan.nextLong();
		System.out.println(boufing(a,b));

	}

}

import java.util.Scanner;
public class test {
    public static void main(String[] args) {

        Scanner s=new Scanner(System.in);
        long a=s.nextLong();
        long b=s.nextLong();
        long sum=1;
        long g=b%10;
        for(long i=(b-a);i>0;i--){
            sum=(sum*g)%10;
            g--;
            if(sum==0)
                break;
        }

        System.out.println(sum%10);

    }
}

import java.math.BigInteger;
import java.util.*;
import java.util.stream.IntStream;
import java.util.stream.Stream;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        long a = in.nextLong();
        long b = in.nextLong();

        if (b - a > 9) {
            System.out.println(0);
            return;
        }
        if (a == b) {
            System.out.println(1);
            return;
        }

        if (b - a == 1) {
            System.out.println(b % 10);
            return;
        }

        long start = a + 1;
        if (start % 10 == 1 && b % 10 == 2 || start % 10 == 3 && b % 10 == 4 || start % 10 == 6 && b % 10 == 7
                || start % 10 == 8 && b % 10 == 9) {
            System.out.println(2);
        } else if ((start % 10 == 1 || start % 10 == 2) && b % 10 == 3
                || start % 10 == 6 && b % 10 == 8) {
            System.out.println(6);
        } else if ((start % 10 == 1 || start % 10 == 2) && b % 10 == 4 ||
                start % 10 == 6 && b % 10 == 9 || start % 10 == 7 && b % 10 == 9) {
            System.out.println(4);
        }  else {
            System.out.println(0);
        }
    }
}

import java.util.*;
import java.io.*;

public class Main {
  public static void main (String[] args) {
    Scanner sc = new Scanner(System.in);
    //BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    OutputStream out = new BufferedOutputStream ( System.out );
    String n = sc.next();
    String m = sc.next();
    int a = Integer.parseInt("" + n.charAt(n.length()-1));
    int b = Integer.parseInt("" + m.charAt(m.length()-1));
    int ans = -1;
    if(((n.length() > 1 && m.length() > 1
        && Integer.parseInt("" + n.charAt(n.length()-2)) <
        Integer.parseInt("" + m.charAt(m.length()-2))) || a >= b ||
       (n.length() < m.length() )) && !n.equals(m)) {
      ans = 0;
    }
    else {
      int temp = 1;
      for(int i = b; i > a; i--) {
      temp *= i;
      }
      ans = temp % 10;
    }
    System.out.println(ans);
  }
}

import java.util.Scanner;

public class dragonyears {
	static long a, b;
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		a = sc.nextLong(); b = sc.nextLong();

		long num;

		num = fact(b);
		System.out.println(num % 10);

	}

	private static long fact(long dif) {
		if(dif == 0) return 1;
		if(dif == 1) return b;
		long fact = 1;
		while(dif > a) {
			fact *= dif;
			fact %= 10;
			if(fact == 0) return 0;
			dif--;
		}
		return fact;
	}

}

import java.util.Scanner;

public class Main  {
    public static void main(String[] args) {
        long num1;
        long num2;
        long result = 1;
        Scanner kbd = new Scanner(System.in);
        num1 = kbd.nextLong();
        num2 = kbd.nextLong();
        long diff = num2-num1;

        if (num1 == 0) {
            num1 = 1;
        }

        for (int i=0; i<diff; i++){
            if (result == 0) {
                break;
            }
            result *= (num2%10);
            result %= 10;
            num2--;
        }

        System.out.println(result%10);
    }
}

import java.util.*;

public class Immortality {
	public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        long x = 0;

        long a = sc.nextLong();
        long b = sc.nextLong();

        long fact = 1;

        for(long i = a + 1; i <= b; i++){
            fact = (fact % 10) * (i % 10);
            if(fact % 10 == 0){
                break;
            }
        }

        System.out.println(fact % 10);

	}

}

import java.util.*;
import java.lang.*;
import java.io.*;

public class R439B  {
    public static void main (String[] args) throws java.lang.Exception {
        InputReader in = new InputReader(System.in);
        PrintWriter w = new PrintWriter(System.out);
        long a=Math.max(1,in.nextLong()),b=Math.max(1,in.nextLong());
        long ans=1;
        for(long i=b;i>a;i--){
            ans=(ans*(i%10))%10;
            //w.println(ans);
            if (ans==0)
                break;
        }
        w.println(ans);
        w.close();
    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1)
                throw new UnknownError();
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new UnknownError();
                }
                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public int peek() {
            if (numChars == -1)
                return -1;
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    return -1;
                }
                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar];
        }

        public void skip(int x) {
            while (x-- > 0)
                read();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public String nextString() {
            return next();
        }

        public String next() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuffer res = new StringBuffer();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));

            return res.toString();
        }

        public String nextLine() {
            StringBuffer buf = new StringBuffer();
            int c = read();
            while (c != '\n' && c != -1) {
                if (c != '\r')
                    buf.appendCodePoint(c);
                c = read();
            }
            return buf.toString();
        }

        public double nextDouble() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E')
                    return res * Math.pow(10, nextInt());
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E')
                        return res * Math.pow(10, nextInt());
                    if (c < '0' || c > '9')
                        throw new InputMismatchException();
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }
        public int[] nextIntArray(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++)
                a[i] = nextInt();
            return a;
        }
        public long[] nextLongArray(int n) {
            long[] a = new long[n];
            for (int i = 0; i < n; i++)
                a[i] = nextLong();
            return a;
        }
        public boolean hasNext() {
            int value;
            while (isSpaceChar(value = peek()) && value != -1)
                read();
            return value != -1;
        }

        private boolean isSpaceChar(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

    }
}

import java.util.*;
public class Immorality{
public static void main(String args[]){

Scanner sc = new Scanner(System.in);
		long x;
		long y;
		long z;
		long w;
		long s=1;
		x = sc.nextLong();
		y = sc.nextLong();
		for(z=x+1;z<=y;z++){
			w=z%10;
			s*=w;
			if(s==0)
				break;
		}
		System.out.println(s%10);
    }
}

import java.io.PrintWriter;
import java.util.Scanner;

public class phoenix {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out, true);

		long a = (in.nextLong() + 1);
		long b = in.nextLong();

		if (b - a > 10)
		{
			out.println(0);
			System.exit(0);
		}

		long fact = 1;

		for (; a <= b ; a++)
		{
			fact = (fact * (a % 10)) % 10;
		}

		out.println(fact % 10);

		in.close();
	}

}

/*
######  ######    #####  ######  ######  #####
 #   #  #    #      #    #    #  #    #    #
 #   #  # #  #      #    # ## #  # ## #    #
 #   #  #  #    #   #    #    #  #    #    #
######  #   #   # # #    #    #  #    #    #
 */
import java.util.*;
import java.io.*;
public class factorial {
    public static void main(String args[] ) throws Exception {
        Scanner scan = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        long t = scan.nextLong();
        long t1 = scan.nextLong();
        long res = t1-t;
        long fact =1;
        long ans = 1;
        for(long i=t+1;i <= t1 ;i++){
            ans *= i %10;
            if(ans==0){
                break;
            }
        }
        String ans1 = ""+ans;
        System.out.println(ans1.charAt(ans1.length()-1));

    }

}

import java.io.*;
import java.util.Locale;
import java.util.StringTokenizer;

public class B {

    private void solve() throws IOException {
        long a = nextLong();
        long b = nextLong();
        long ans = 0;
        if (b - a < 5) {
            ans = 1;
            for (long i = a + 1; i <= b; i++) {
                ans = (ans * (i % 10)) % 10;
            }
        }
        System.out.println(ans);
    }

    private void run() {
        try {
            br = new BufferedReader(new InputStreamReader(System.in));

            solve();

        } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }
    }

    private BufferedReader br;
    private StringTokenizer in;

    private String nextToken() throws IOException {
        while (in == null || !in.hasMoreTokens()) {
            in = new StringTokenizer(br.readLine());
        }
        return in.nextToken();
    }

    private int nextInt() throws IOException {
        return Integer.parseInt(nextToken());
    }

    private double nextDouble() throws IOException {
        return Double.parseDouble(nextToken());
    }

    private long nextLong() throws IOException {
        return Long.parseLong(nextToken());
    }

    public static void main(String[] args) throws IOException {
        Locale.setDefault(Locale.US);
        new B().run();
    }

}

import java.util.*;

public class Main2 {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        long a = in.nextLong();
        long b = in.nextLong();

        long f = 1;
        for (long e = a + 1; e <= b; e++) {
            f *= e % 10;
            if (f % 10 == 0) {
                System.out.print(0);
                return;
            }
        }

        System.out.print(f % 10);
    }
}

import java.io.*;
import java.lang.reflect.Array;
import java.util.*;

public class A1008 {
    public static void main(String [] args) /*throws Exception*/ {
        InputStream inputReader = System.in;
        OutputStream outputReader = System.out;
        InputReader in = new InputReader(inputReader);//new InputReader(new FileInputStream(new File("input.txt")));new InputReader(inputReader);
        PrintWriter out = new PrintWriter(outputReader);//new PrintWriter(new FileOutputStream(new File("output.txt")));
        Algorithm solver = new Algorithm();
        solver.solve(in, out);
        out.close();
    }
}

class Algorithm {
    void solve(InputReader ir, PrintWriter pw) {

        long a = ir.nextLong(), b = ir.nextLong();
        long lastDigit = 1;

        if (b - a > 9) pw.print(0);
        else {
            for (long i = a + 1; i <= b; i++) {
                lastDigit = (lastDigit * (i % 10)) % 10;
            }

            pw.print(lastDigit);
        }

    }
}

class InputReader {
    private BufferedReader reader;
    private StringTokenizer tokenizer;

    InputReader(InputStream stream) {
        reader = new BufferedReader(new InputStreamReader(stream), 32768);
        tokenizer = null;
    }

    String next() {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    }

    String nextLine(){
        String fullLine = null;
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                fullLine = reader.readLine();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
            return fullLine;
        }
        return fullLine;
    }

    String [] toArray() {
        return nextLine().split(" ");
    }

    int nextInt() {
        return Integer.parseInt(next());
    }
    double nextDouble() {
        return Double.parseDouble(next());
    }
    long nextLong() {
        return Long.parseLong(next());
    }

}

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		long ans = 1;
		Scanner br = new Scanner(System.in);
		long a = br.nextLong();
		long b = br.nextLong();
		for(long i=a+1;i<=b;i++){
			ans *= i;
			ans %= 10;
			if(ans==0){
				break;
			}
		}
		System.out.println(ans);
	}

}

import java.io.*;
import java.util.*;
public class B869
{

    public static void main(String args[])throws IOException
    {
        BufferedReader br= new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out= new PrintWriter(System.out);
        //double a=in.nextDouble();
        //double b=in.nextDouble();
        StringTokenizer str= new StringTokenizer(br.readLine());
        String a1= str.nextToken();
        String b1= str.nextToken();

        if(a1.equals(b1))
        {
            out.println(1);
            out.flush();
            return;
        }
        int i=0;
        if(a1.length()==b1.length())
        {
            for(i=0; i< a1.length(); i++)
            {
                if(a1.charAt(i)!=b1.charAt(i))
                {
                    break;
                }
            }
        }
        double a= Double.parseDouble(a1.substring(i));
        double b= Double.parseDouble(b1.substring(i));
        double prod=1;

        if(a+1==b)
        prod=b%10;
        else
        {
            x:
            for(i=(int)a+1; i<=b; i++)
            {
                prod*= i%10;
                prod= prod%10;
                if(prod==0)
                break x;
            }
        }
        out.println((long)prod);
        out.flush();
    }

}

import java.util.Scanner;

public class problemooobBB {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		long a = scan.nextLong();
		long b = scan.nextLong();

		long s = 1;;

		for (long c = a+1; c <= b; c++) {
			s *= c;
			s %= 10;

			if (s == 0) {
				System.out.println(0);
				return;
			}
		}
		System.out.println(s);

	}

}

import java.util.*;
/**
 * Created by CUONG on 10/8/2017.
 */
public class PS869B {
    public static void main(String[] args)
    {
        Scanner s= new Scanner(System.in);
        long a= s.nextLong();
        long b= s.nextLong();
        int c= (int)(b%10); int d= (int)(a%10);
        long diff= (b-a); int ans=0;
        if (diff<5)
        {
            int temp=1;
            for (int i=c; i>c-diff; i--)
            {
                temp*=i;
            }
            ans= temp%10;
        }

        System.out.println(ans);
    }
}

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author kangtaku
 */
public class Main {
  public static void main(String[] args) {
    InputStream inputStream = System.in;
    OutputStream outputStream = System.out;
    InputReader in = new InputReader(inputStream);
    PrintWriter out = new PrintWriter(outputStream);
    TaskB solver = new TaskB();
    solver.solve(1, in, out);
    out.close();
  }

  static class TaskB {
    public void solve(int testNumber, InputReader in, PrintWriter out) {
      String a = in.readToken(), b = in.readToken();
      int aLast = a.charAt(a.length() - 1) - '0';
      int c = aLast;
      BigInteger ba = new BigInteger(a);
      BigInteger bb = new BigInteger(b);
      BigInteger bc = bb.subtract(ba);
      int dif;
      if (bc.compareTo(BigInteger.valueOf(5L)) > 0) {
        out.println("0");
      } else {
        dif = bc.intValue();
        int cc = c + 1;
        c = 1;
        for (int i = 0; i < dif; i++) {
          c = c * cc;
          cc++;
        }
        String aa = String.valueOf(c);
        out.println(aa.charAt(aa.length() - 1));
      }
    }

  }

  static class InputReader {
    private InputStream stream;
    private BufferedReader br = null;
    private byte[] buf = new byte[1024];
    private int curChar;
    private int numChars;

    public InputReader(InputStream stream) {
      this.stream = stream;
      this.br = new BufferedReader(new InputStreamReader(stream));
    }

    public int read() {
      if (numChars == -1)
        throw new InputMismatchException();
      if (curChar >= numChars) {
        curChar = 0;
        try {
          numChars = stream.read(buf);
        } catch (IOException e) {
          throw new InputMismatchException();
        }
        if (numChars <= 0)
          return -1;
      }
      return buf[curChar++];
    }

    public String readToken() {
      int c;
      while (isSpaceChar(c = read())) ;
      StringBuilder result = new StringBuilder();
      result.appendCodePoint(c);
      while (!isSpaceChar(c = read()))
        result.appendCodePoint(c);
      return result.toString();
    }

    public boolean isSpaceChar(int c) {
      return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    }

  }
}

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author kangtaku
 */
public class Main {
  public static void main(String[] args) {
    InputStream inputStream = System.in;
    OutputStream outputStream = System.out;
    InputReader in = new InputReader(inputStream);
    PrintWriter out = new PrintWriter(outputStream);
    TaskB solver = new TaskB();
    solver.solve(1, in, out);
    out.close();
  }

  static class TaskB {
    public void solve(int testNumber, InputReader in, PrintWriter out) {
      long a = in.readLong(), b = in.readLong();
      long ans = 1;
      for (long i = a + 1; i <= b && ans != 0; i++) {
        ans = (ans * i) % 10;
      }
      out.println(ans);
    }

  }

  static class InputReader {
    private InputStream stream;
    private BufferedReader br = null;
    private byte[] buf = new byte[1024];
    private int curChar;
    private int numChars;

    public InputReader(InputStream stream) {
      this.stream = stream;
      this.br = new BufferedReader(new InputStreamReader(stream));
    }

    public int read() {
      if (numChars == -1)
        throw new InputMismatchException();
      if (curChar >= numChars) {
        curChar = 0;
        try {
          numChars = stream.read(buf);
        } catch (IOException e) {
          throw new InputMismatchException();
        }
        if (numChars <= 0)
          return -1;
      }
      return buf[curChar++];
    }

    public long readLong() {
      int c = read();
      while (isSpaceChar(c))
        c = read();
      int sgn = 1;
      if (c == '-') {
        sgn = -1;
        c = read();
      }
      long res = 0;
      do {
        if (c < '0' || c > '9')
          throw new InputMismatchException();
        res *= 10;
        res += c - '0';
        c = read();
      } while (!isSpaceChar(c));
      return res * sgn;
    }

    public boolean isSpaceChar(int c) {
      return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    }

  }
}

import java.io.*;
import java.util.*;
import java.math.BigInteger;
public class B2
{
    public static void main(String[] args)throws IOException
    {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        String t1=br.readLine();
        String[] t2=t1.split(" ");
        BigInteger a=new BigInteger(t2[0]);
        BigInteger b=new BigInteger(t2[1]);
        BigInteger facta=BigInteger.ONE;
        BigInteger factb=BigInteger.ONE;
        int flag=-1;
        if(a.compareTo(b)==0)
        {
            System.out.println(1);
        }
        else if(a.compareTo(b)>0)
        {
            while(a.compareTo(b)>0)
            {
                facta=facta.multiply(a);
                a=a.subtract(BigInteger.ONE);
                String res=facta.toString();
                if(res.charAt(res.length()-1)=='0')
                {
                    System.out.println(0);
                    flag=1;
                    break;
                }
            }
            if(flag==-1)
            {
                String res=facta.toString();
                System.out.println(res.charAt(res.length()-1));
            }
        }
        else if(b.compareTo(a)>0)
        {
            BigInteger temp=a;
            a=b;
            b=temp;
            while(a.compareTo(b)>0)
            {
                facta=facta.multiply(a);
                a=a.subtract(BigInteger.ONE);
                String res=facta.toString();
                if(res.charAt(res.length()-1)=='0')
                {
                    System.out.println(0);
                    flag=1;
                    break;
                }
            }
            if(flag==-1)
            {
                String res=facta.toString();
                System.out.println(res.charAt(res.length()-1));
            }
        }
    }
}

import java.util.*;

import java.awt.List;
import java.io.*;
import java.lang.*;

public class code3
	{

		public static void main(String[] args)
		{
			InputReader in = new InputReader(System.in);
			PrintWriter pw = new PrintWriter(System.out);

			//Code starts..

			long a = in.nextLong();
			long b = in.nextLong();

			if(b-a>5)
				pw.println(0);
			else
			{
				long dif = b-a;
				long tmp = 1;
				while(dif-->0)
				{

					tmp *=  (b--)%10;
					tmp %= 10;
				//	pw.println(tmp);
				}

				pw.println(tmp%10);

			}

			//Code ends....

			pw.flush();
			pw.close();
		}

		public static boolean isSubSequence(char[] str2,  String str1)
		{

			int j = 0;
			int m = str1.length();
			int n = str2.length;

			for (int i = 0; i < n && j < m; i++)

				if (str1.charAt(j) == str2[i])

					j++;

			return (j == m);
  }

		static class InputReader
		{

			private final InputStream stream;
			private final byte[] buf = new byte[8192];
			private int curChar, snumChars;
			private SpaceCharFilter filter;

			public InputReader(InputStream stream)
			{
				this.stream = stream;
			}

			public int snext()
			{
				if (snumChars == -1)
					throw new InputMismatchException();
				if (curChar >= snumChars)
				{
					curChar = 0;
					try
					{
						snumChars = stream.read(buf);
					}
					catch (IOException e)
					{
						throw new InputMismatchException();
					}
					if (snumChars <= 0)
						return -1;
				}
				return buf[curChar++];
			}

			public int nextInt()
		    {
				int c = snext();
				while (isSpaceChar(c))
				{
					c = snext();
				}
				int sgn = 1;
				if (c == '-')
			    {
					sgn = -1;
					c = snext();
				}
				int res = 0;
				do
				{
					if (c < '0' || c > '9')
						throw new InputMismatchException();
					res *= 10;
					res += c - '0';
					c = snext();
				} while (!isSpaceChar(c));
				return res * sgn;
			}

			public long nextLong()
		    {
				int c = snext();
				while (isSpaceChar(c))
				{
					c = snext();
				}
				int sgn = 1;
				if (c == '-')
				{
					sgn = -1;
					c = snext();
				}
				long res = 0;
				do
				{
					if (c < '0' || c > '9')
						throw new InputMismatchException();
					res *= 10;
					res += c - '0';
					c = snext();
				} while (!isSpaceChar(c));
				return res * sgn;
			}

			public int[] nextIntArray(int n)
			{
				int a[] = new int[n];
				for (int i = 0; i < n; i++)
				{
					a[i] = nextInt();
				}
				return a;
			}

			public String readString()
		    {
				int c = snext();
				while (isSpaceChar(c))
				{
					c = snext();
				}
				StringBuilder res = new StringBuilder();
				do
				{
					res.appendCodePoint(c);
					c = snext();
				} while (!isSpaceChar(c));
				return res.toString();
			}

			public String nextLine()
			{
				int c = snext();
				while (isSpaceChar(c))
					c = snext();
				StringBuilder res = new StringBuilder();
				do
				{
					res.appendCodePoint(c);
					c = snext();
				} while (!isEndOfLine(c));
				return res.toString();
			}

			public boolean isSpaceChar(int c)
			{
				if (filter != null)
					return filter.isSpaceChar(c);
				return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
			}

			private boolean isEndOfLine(int c)
			{
				return c == '\n' || c == '\r' || c == -1;
			}

			public interface SpaceCharFilter
		    {
				public boolean isSpaceChar(int ch);
			}
		}
		public static long c = 0;

		public static long mod = 1000000007;
		public static int d;
		public static int p;
		public static int q;
		public static boolean flag;
		public static long INF= Long.MAX_VALUE;

		public static void factSieve(int[] a, int n) {

			for(int i=2; i<=n; i+=2)
				a[i] = 2;

			for(int i=3; i<=n; i+=2)
			{
				if(a[i]==0)
				{
					a[i] = i;

					for(int j=i; j*i<=n; j++)
					{
						a[i*j] = i;
					}
				}
			}

			int k = 1000;
			while(k!=1)
			{
				System.out.print(a[k]+" ");
				k /= a[k];

			}
		}

		public static long floorsqrt(long n) {
			long ans = 0;
			long l = 0;
			long r = n;
			long mid = 0;
			while(l<=r)
			{
				mid = (l+r)/2;
				if(mid*mid==n)
					return mid;

				if(mid*mid>n)
				{
					r = mid-1;
				}
				else
				{
					ans = mid;
					l = mid+1;
				}

			}

			return ans;
		}

		public static long fun(int[] a, int[] b, int m,int n) {
			long result =0;
			for(int i=0; i<m; i++)
				for(int j=0; j<m; j++)
				{
					long[] fib  = new long[Math.max(2, n+2)];
					fib[1] = a[i];
					fib[2] = b[j];
					for(int k=3; k<=n; k++)
						fib[k] = (fib[k-1]%mod + fib[k-2]%mod)%mod;
					result = (result%mod + fib[n]%mod)%mod;
				}

			return result;

		}

		public static double slope(pair p1, pair p2)
		{
			double m = INF;
			if((p1.x - p2.x)!=0)
			m =  p1.y - p2.y/(p1.x - p2.x);

			return Math.abs(m);

		}

		public static int count(String[] s, int f)
		{
			int count = 0;
			int n = s[0].length();

			if(f==1)
			{
			for(int i = 0; i<n; i++)
			{
				for(int j=0; j<n; j++)
				{
					if(i%2==0)
					{
						if(j%2==0 && s[i].charAt(j)=='0')
							count++;
						if(j%2==1 && s[i].charAt(j)=='1')
							count++;
					}
					if(i%2==1)
					{
						if(j%2==1 && s[i].charAt(j)=='0')
							count++;
						if(j%2==0 && s[i].charAt(j)=='1')
							count++;
					}

				}
			}
			}
			else
			{

			 count = 0;

			for(int i = 0; i<n; i++)
			{
				for(int j=0; j<n; j++)
				{
					if(i%2==1)
					{
						if(j%2==0 && s[i].charAt(j)=='0')
							count++;
						if(j%2==1 && s[i].charAt(j)=='1')
							count++;
					}
					if(i%2==0)
					{
						if(j%2==1 && s[i].charAt(j)=='0')
							count++;
						if(j%2==0 && s[i].charAt(j)=='1')
							count++;
					}

				}
			}

			}

			return count;

		}

		public static  int gcd(int p2, int p22)
		{
		    if (p2 == 0)
		        return (int) p22;
		    return gcd(p22%p2, p2);
		}

		public static int findGCD(int arr[], int n)
		{
		    int result = arr[0];
		    for (int i=1; i<n; i++)
		        result = gcd(arr[i], result);

		    return result;
		}

		public static void nextGreater(long[] a, int[] ans)
		{

			Stack<Integer> stk = new Stack<>();
			stk.push(0);

			for(int i=1; i<a.length; i++)
			{

				if(!stk.isEmpty())
				{
				int s = stk.pop();
				while(a[s]<a[i])
				{
					ans[s] = i;
					if(!stk.isEmpty())
						s = stk.pop();
					else
						break;
				}
				if(a[s]>=a[i])
					stk.push(s);
				}

				stk.push(i);

			}
			return;

		}

		public static void nextGreaterRev(long[] a, int[] ans)
		{

			int n = a.length;
			int[] pans = new int[n];
			Arrays.fill(pans, -1);
			long[] arev = new long[n];
			for(int i=0; i<n; i++)
				arev[i] = a[n-1-i];

			Stack<Integer> stk = new Stack<>();
			stk.push(0);

			for(int i=1; i<n; i++)
			{

				if(!stk.isEmpty())
				{
				int s = stk.pop();
				while(arev[s]<arev[i])
				{
					pans[s] = n - i-1;
					if(!stk.isEmpty())
						s = stk.pop();
					else
						break;
				}
				if(arev[s]>=arev[i])
					stk.push(s);
				}

				stk.push(i);

			}

			//for(int i=0; i<n; i++)
				//System.out.print(pans[i]+" ");

			for(int i=0; i<n; i++)
				ans[i] = pans[n-i-1];

			return;

		}

		public static void nextSmaller(long[] a, int[] ans)
		{

			Stack<Integer> stk = new Stack<>();
			stk.push(0);

			for(int i=1; i<a.length; i++)
			{

				if(!stk.isEmpty())
				{
				int s = stk.pop();
				while(a[s]>a[i])
				{
					ans[s] = i;
					if(!stk.isEmpty())
						s = stk.pop();
					else
						break;
				}
				if(a[s]<=a[i])
					stk.push(s);
				}

				stk.push(i);

			}
			return;

		}

	    public static long lcm(int[] numbers) {
	        long lcm = 1;
	        int divisor = 2;
	        while (true) {
	            int cnt = 0;
	            boolean divisible = false;
	            for (int i = 0; i < numbers.length; i++) {
	                if (numbers[i] == 0) {
	                    return 0;
	                } else if (numbers[i] < 0) {
	                    numbers[i] = numbers[i] * (-1);
	                }
	                if (numbers[i] == 1) {
	                    cnt++;
	                }
	                if (numbers[i] % divisor == 0) {
	                    divisible = true;
	                    numbers[i] = numbers[i] / divisor;
	                }
	            }
	            if (divisible) {
	                lcm = lcm * divisor;
	            } else {
	                divisor++;
	            }
	            if (cnt == numbers.length) {
	                return lcm;
	            }
	        }
	    }
		public static long fact(long n) {

			long factorial = 1;
			 for(int i = 1; i <= n; i++)
		        {
		            factorial *= i;
		        }
			 return factorial;
		}

		public static int lowerLimit(int[] a, int n) {
			int ans = 0;

			int ll = 0;
			int rl = a.length-1;
		//	System.out.println(a[rl]+" "+n);
			if(a[0]>n)
				return 0;
			if(a[0]==n)
				return 1;
			else if(a[rl]<=n)
				return rl+1;

			while(ll<=rl)
			{

				int mid = (ll+rl)/2;
				if(a[mid]==n)
				{
					ans = mid + 1;
					break;
				}

				else if(a[mid]>n)
				{
					rl = mid-1;

				}
				else
				{
					ans = mid+1;
					ll = mid+1;
				}
			}

			return ans;
		}

		public static long choose(long total, long choose){
		    if(total < choose)
		        return 0;
		    if(choose == 0 || choose == total)
		        return 1;
		    return (choose(total-1,choose-1)+choose(total-1,choose))%mod;
		}

		public static int[] suffle(int[] a,Random gen)
		{
			int n = a.length;
			for(int i=0;i<n;i++)
			{
				int ind = gen.nextInt(n-i)+i;
				int temp = a[ind];
				a[ind] = a[i];
				a[i] = temp;
			}
			return a;
		}

		public static int floorSearch(int arr[], int low, int high, int x)
		{
		    if (low > high)
		        return -1;

		    if (x > arr[high])
		        return high;
		    int mid = (low+high)/2;

		    if (mid > 0 && arr[mid-1] < x && x < arr[mid])
		        return mid-1;

		    if (x < arr[mid])
		        return floorSearch(arr, low, mid-1, x);

		    return floorSearch(arr, mid+1, high, x);
		}

		public static void swap(int a, int b){
			int temp = a;
			a = b;
			b = temp;
		}
		public static ArrayList<Integer> primeFactorization(int n)
		{
			ArrayList<Integer> a =new ArrayList<Integer>();
			for(int i=2;i*i<=n;i++)
			{
				while(n%i==0)
				{
					a.add(i);
					n/=i;
				}
			}
			if(n!=1)
				a.add(n);
			return a;
		}

		public static void sieve(boolean[] isPrime,int n)
		{
			for(int i=1;i<n;i++)
				isPrime[i] = true;

			isPrime[0] = false;
			isPrime[1] = false;

			for(int i=2;i*i<n;i++)
			{
				if(isPrime[i] == true)
				{
					for(int j=(2*i);j<n;j+=i)
						isPrime[j] = false;
				}
			}
		}

		public static int lowerbound(ArrayList<Long> net, long c2) {
			int i=Collections.binarySearch(net, c2);
			if(i<0)
				i = -(i+2);
			return i;

		}
		public static int uperbound(ArrayList<Integer> list, int c2) {
			int i=Collections.binarySearch(list, c2);
			if(i<0)
				i = -(i+1);
			return i;

		}
		public static int uperboundArray(int[] dis, int c2) {
			int i=Arrays.binarySearch(dis, c2);
			if(i<0)
				i = -(i+1);
			return i;

		}

		public static long[] sort(long[] a)
		{
			Random gen = new Random();
			int n = a.length;
			for(int i=0;i<n;i++)
			{
				int ind = gen.nextInt(n-i)+i;
				long temp = a[ind];
				a[ind] = a[i];
				a[i] = temp;
			}

			Arrays.sort(a);
			return a;
		}

		public static int[] sort(int[] a)
		{
			Random gen = new Random();
			int n = a.length;
			for(int i=0;i<n;i++)
			{
				int ind = gen.nextInt(n-i)+i;
				int temp = a[ind];
				a[ind] = a[i];
				a[i] = temp;
			}

			Arrays.sort(a);
			return a;
		}

		public static int GCD(int a,int b)
		{
			if(b==0)
				return a;
			else
				return GCD(b,a%b);
		}

		public static long GCD(long a,long b)
		{
			if(b==0)
				return a;
			else
				return GCD(b,a%b);
		}

		public static void extendedEuclid(int A,int B)
		{
			if(B==0)
			{
				d = A;
				p = 1 ;
				q = 0;
			}
			else
			{
				extendedEuclid(B, A%B);
				int temp = p;
				p = q;
				q = temp - (A/B)*q;
			}
		}

		public static long LCM(long a,long b)
		{
			return (a*b)/GCD(a,b);
		}

		public static int LCM(int a,int b)
		{
			return (a*b)/GCD(a,b);
		}

		public static int binaryExponentiation(int x,int n)
		{
		    int result=1;
		    while(n>0)
		    {
		        if(n % 2 ==1)
		            result=result * x;
		        x=x*x;
		        n=n/2;
		    }
		    return result;
		}

		public static int[] countDer(int n)
	    {
	        int der[] = new int[n + 1];

	        der[0] = 1;
	        der[1] = 0;
	        der[2] = 1;

	        for (int i = 3; i <= n; ++i)
	            der[i] = (i - 1) * (der[i - 1] + der[i - 2]);

	        // Return result for n
	        return der;
	    }

		 static long binomialCoeff(int n, int k)
		    {
		    long C[][] = new long[n+1][k+1];
		    int i, j;

		        // Calculate  value of Binomial Coefficient in bottom up manner
		    for (i = 0; i <= n; i++)
		    {
		        for (j = 0; j <= Math.min(i, k); j++)
		        {
		            // Base Cases
		            if (j == 0 || j == i)
		                C[i][j] = 1;

		            // Calculate value using previosly stored values
		            else
		                C[i][j] = C[i-1][j-1] + C[i-1][j];
		          }
		     }

		    return C[n][k];
		    }

		public static long binaryExponentiation(long x,long n)
		{
		    long result=1;
		    while(n>0)
		    {
		        if(n % 2 ==1)
		            result=result * x;
		        x=(x%mod * x%mod)%mod;
		        n=n/2;
		    }
		    return result;
		}

		public static int modularExponentiation(int x,int n,int M)
		{
		    int result=1;
		    while(n>0)
		    {
		        if(n % 2 ==1)
		            result=(result * x)%M;
		        x=(x*x)%M;
		        n=n/2;
		    }
		    return result;
		}

		public static long modularExponentiation(long x,long n,long M)
		{
		    long result=1;
		    while(n>0)
		    {
		        if(n % 2 ==1)
		            result=(result * x)%M;
		        x=(x*x)%M;
		        n=n/2;
		    }
		    return result;
		}

		public static int modInverse(int A,int M)
		{
		    return modularExponentiation(A,M-2,M);
		}

		public static long modInverse(long A,long M)
		{
		    return modularExponentiation(A,M-2,M);
		}

		public static boolean checkYear(int year)
	    {
			if (year % 400 == 0)
	            return true;

	        if (year % 100 == 0)
	            return false;

	        if (year % 4 == 0)
	            return true;
	        return false;
	    }

		public static boolean isPrime(int n)
		{

		    if (n <= 1)  return false;
		    if (n <= 3)  return true;

		    if (n%2 == 0 || n%3 == 0)
		    	return false;

		    for (int i=5; i*i<=n; i=i+6)
		    {
		        if (n%i == 0 || n%(i+2) == 0)
		           return false;
		    }

		    return true;
		}

		static class pair implements Comparable<pair>

		{
			Integer x, y;
			pair(int x,int y)
			{
				this.x=x;
				this.y=y;
			}

			public int compareTo(pair o) {
				int result = x.compareTo(o.x);
				if(result==0)
					result = y.compareTo(o.y);

				return result;
			}

			public String toString()
			{
				return x+" "+y;
			}

			public boolean equals(Object o)
			{
				if (o instanceof pair)
			    {
					pair p = (pair)o;
					return p.x == x && p.y == y ;
				}
				return false;
			}

			public int hashCode()
			{
				return new Long(x).hashCode()*31 + new Long(y).hashCode();
			}
		}

		static class triplet implements Comparable<triplet>
		{
			Integer x,y,z;
			triplet(int x,int y,int z)
			{
				this.x = x;
				this.y = y;
				this.z = z;
			}

			public  int compareTo(triplet o)
			{
				int result = x.compareTo(o.x);
				if(result==0)
					result =  y.compareTo(o.y);
				if(result==0)
					result = z.compareTo(o.z);

				return result;
			}

			public boolean equlas(Object o)
			{
				if(o instanceof triplet)
				{
					triplet p = (triplet)o;
					return x==p.x && y==p.y && z==p.z;
				}
				return false;
			}

			public String toString()
			{
				return x+" "+y+" "+z;
			}
			public int hashCode()
			{
				return new Long(x).hashCode()*31 + new Long(y).hashCode() + new Long(z).hashCode();
			}
		}

		static class node implements Comparable<node>

		{
			Integer x, y, z;
			node(int x,int y, int z)
			{
				this.x=x;
				this.y=y;
				this.z=z;
			}

			public int compareTo(pair o) {
				int result = x.compareTo(o.x);
				if(result==0)
					result = y.compareTo(o.y);
				if(result==0)
					result = z.compareTo(z);
				return result;
			}

			@Override
			public int compareTo(node o) {
				// TODO Auto-generated method stub
				return 0;
			}
		}
	}

import java.util.Scanner;

public class xxx_869B {
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        long a = s.nextLong(), b=s.nextLong();
        long diff = b-a;
        if(diff>5) // must include a (5 with an even number) or a (10)
        {
            System.out.println(0);
        }
        else if(diff==1)  //  b!/(b-1)! = b
        {
            System.out.println(b%10);

        }
        else if(diff==0)  //  b!/b! = 1
        {
            System.out.println(1);
        }
        else // diff: 2,3,4  // do it manually !
        {
            long res=1;
            for (long x = b; x > a ; x--) {
                res*=x;
                res%=10;
            }
            System.out.println(res%10);
        }

    }
}

import java.io.*;
import java.util.*;
import java.math.*;
public class GFG {
	public static void main (String[] args) {
		Scanner sc=new Scanner(System.in);
		BigInteger a=sc.nextBigInteger();
		BigInteger b=sc.nextBigInteger();
		BigInteger c=b.subtract(a);
		BigInteger ten=new BigInteger("10");
		BigInteger five=new BigInteger("5");
		int x=c.compareTo(five);
		if(x==1)
		System.out.println("0");
		else if(x==0){
		    System.out.println("0");
		}else{
		    int m1=(a.mod(ten)).intValue();
		    int m2=(b.mod(ten)).intValue();
		    int d=m2-m1;
		    if(d<0)
		    System.out.println("0");
		    else
		    {
		        int ans=1;
		        for(int i=m1+1;i<=m2;i++)
		        ans*=i;
		        System.out.println(ans%10);
		    }
		}
	}
}

import java.util.*;
public class Main {
  public static void main(String[] args) {
    Scanner input = new Scanner(System.in);
    long n = input.nextLong();
    long m = input.nextLong();
    long mult = 1;
    if(m-n>=10)
      System.out.println("0");
    else
    {
      for(long i=m;i>n;i--)
        mult = (mult*(i%10))%10;
      System.out.println(mult);
    }
  }
}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.*;

public class Hello {
    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            return str;
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        long nextLong() {

            return Long.parseLong(next());
        }

        BigInteger nextBigIntger() {
            BigInteger bb = new BigInteger(next());
            return bb;
        }
    }
 static long MOD = 1000000007;
    public static void main(String[] args) {
        FastReader sc = new FastReader();
        long a = sc.nextLong();
        long b = sc.nextLong();
        if(b==a)
            System.out.println(1);
        else {
            long ans=b%10,diff=b-a;
            while(diff>1){
                if(ans==0)
                    break;
                long tt = (b-1)%10;
                ans =(ans*(tt))%(MOD);
                b--;
                diff--;
            }
            System.out.println(ans%10);
        }

    }
}

import java.math.BigInteger;
import java.util.Scanner;

public class B {
	public static void main(String[]args){
		Scanner sc = new Scanner(System.in);
		BigInteger bg = sc.nextBigInteger();
		BigInteger bg2 = sc.nextBigInteger();
		BigInteger bg3 = BigInteger.ONE;
		while(!(bg.equals(bg2))){
			bg=bg.add(BigInteger.ONE);
			bg3=bg3.multiply(bg);
			String temp = bg3+"";
			if((temp.charAt(temp.length()-1)=='0')){
				break;
			}
		}
		System.out.println(bg3.mod(BigInteger.TEN));
	}
}

import java.util.*;
import java.lang.Math;
public class Main
{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		long b = sc.nextLong();
	    if(a==b) System.out.println(1);
		else if(b%10==0) System.out.println(0);
		else if(b-a>=10) System.out.println(0);

		else{
		List<Long> l = new ArrayList<>();
		for(int i=0;i<b-a;i++) l.add(b-i);
		long s=1;
		for(int i=0;i<l.size();i++){
		    s=s*(l.get(i)%10);
		    s=s%10;
		    if(s==0) break;
		}
		System.out.println(s);
	}
	}
}

import java.io.*;

public class B869 {
	public static void main(String[] args) throws IOException {
		BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
		String line = read.readLine();
		long a = Long.parseLong(line.split(" ")[0]);
		long b = Long.parseLong(line.split(" ")[1]);
		if (b / 10 > a / 10) {
			System.out.println(0);
		} else {
			int k = 1;
			for (long i = a % 10 + 1; i <= b % 10; i++) {
				k *= i;
			}
			System.out.println(k % 10);
		}
	}
}

import java.io.*;
import java.util.*;

public class Main
{
      public static void main(String[] args)
      {
            Scanner sc = new Scanner(System.in);

           long n = sc.nextLong();
           long m = sc.nextLong();

           long res = 1;

           for(long i = n+1;i<=m;i++)
           {
                 res = (i%10)*(res%10);

                 if(res%10 == 0)
                 {
                       break;
                 }
           }

           System.out.println(res%10);

      }
}

/*
 * Remember a 2.0 student can know more than a 4.0 student.
 * Grades don't determine intelligence, they test obedience.
 * I Never Give Up.
 */
import java.util.*;
import java.io.*;

import static java.lang.System.out;
//import static java.lang.Math.pow;
//import static java.lang.Math.sqrt;
//import static java.lang.Math.ceil;
//import static java.lang.Math.abs;
//import static java.lang.Math.min;
//import static java.lang.Math.max;
//import static java.lang.Math.floor;
public class ContestMain {
	private static long MOD=1000000007;//10^9+7
	private static final int N=(int) 2e5+5; //200005
	private static Scanner in=new Scanner(System.in);
	private static BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
//	private static ArrayList<Integer> v[]=new ArrayList[N];
//	private static boolean mark[]=new boolean[N];
//	static int choice=Integer.MAX_VALUE,trav=Integer.MAX_VALUE;

	public static void solve(String s){
	}

	public static void main(String[] args) throws IOException{
		long a=in.nextLong();
		long b=in.nextLong();
		if(b-a>=5)out.println(0);
		else{
			int d=Integer.parseInt((""+b).substring((""+b).length()-1));
			int mult=1;
			for(int i=0;i<(b-a);i++){
				mult*=d;
				d--;
			}
			int res=Integer.parseInt((""+mult).substring((""+mult).length()-1));
			out.println(res);
		}
	}
}

import java.util.*;
public class Main
{
     static int fact(int n)
    {
        if(n==0)
        return 1;

        return n*fact(n-1);
    }
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long a=sc.nextLong();
		long b=sc.nextLong();
	long answer = 1;
    if(b - a < 5)
    {
        for(Long i = a + 1; i <= b; i++)
            answer = answer*(i%10);

        answer %= 10;
    }
    else
    {
        answer = 0;
    }
        System.out.println(answer);

	}
}

import java.util.Scanner;

public class Codeforces869B {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        long first = in.nextLong();
        long second = in.nextLong();
        long res = 1;
        for (long i = first + 1; i <= second; i++) {
            if (i % 10 == 0) {
                res = 0;
                break;
            } else {
                res *= i;
                res %= 10;
            }
        }
        System.out.println(res);
    }
}

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskB solver = new TaskB();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskB {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            long a = in.nextLong();
            long b = in.nextLong();

            if (b == a) {
                out.println(1);
                return;
            }
            if (b - a > 10) {
                out.println(0);
                return;
            }

            if (b % 10 == 0 || (a + 1) % 10 == 0) {
                out.println(0);
                return;
            }

            long ans = 1;
            for (long temp = a + 1; temp <= b; ++temp) {
                String req = Long.toString(temp);
                int len = req.length();
                ans *= req.charAt(len - 1) - '0';
            }
            String ansToStr = Long.toString(ans);
            out.println(ansToStr.charAt(ansToStr.length() - 1));
        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private InputReader.SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1) {
                throw new InputMismatchException();
            }
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar++];
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;
            do {
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public boolean isSpaceChar(int c) {
            if (filter != null) {
                return filter.isSpaceChar(c);
            }
            return isWhitespace(c);
        }

        public static boolean isWhitespace(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        }

    }
}

import java.util.Scanner;

public class Main {
    private final static Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) {
        long a = scanner.nextLong();
        long b = scanner.nextLong();
        int remainOfB =(int)(b % 10);
        long difference = b - a;
        if(difference >= 5) {
            System.out.println(0);
        }
        else if (difference == 0){
            System.out.println(1);
        }
        else {
            int res = remainOfB;
            for(int i=1; i<difference; i++) {
                remainOfB -= 1;
                res *= remainOfB;

            }
            res %= 10;
            System.out.println(res);
        }
    }
}

/* package codechef; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.Arrays;
import java.math.BigInteger;

/* Name of the class has to be "Main" only if the class is public. */
public class Main
{
     public static void main (String[] args) throws java.lang.Exception
     {
     	Scanner in =new Scanner(System.in);
		int t=1,n,i,m=0,k,h,p=0,x,o,y;
		String st,s1,s2,s3;
		BigInteger c;
		long a,b,j;
		a=in.nextLong();
		b=in.nextLong();
		if(b-a>=10)
		     System.out.println("0");
		else
          {
     		c=new BigInteger("1");
     		for(j=a+1;j<=b;j++)
     		     c=c.multiply(BigInteger.valueOf(j));
     		BigInteger d=c.mod(BigInteger.valueOf(10));
     		System.out.println(d);
          }
     }
}

import java.io.IOException;
import java.io.InputStream;
import java.math.BigInteger;
import java.io.*;
import java.util.Arrays;

 /*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

///**
 //*
  //* @author aman_robotics
// */
public class like_cs01
{

    public static void main(String [] args)throws IOException
    {
        FastReader in=new FastReader(System.in);
        long a=in.nextLong();
        long b=in.nextLong();
        long p=1;
        for(long i=a+1;i<=b;i++){
            p=p*(i%10);
            p=p%10;
            if(p==0)
            break;
        }
        System.out.println(p);
    }

    static class FastReader{

        byte[] buf = new byte[2048];
        int index, total;
        InputStream in;

        FastReader(InputStream is) {
            in = is;
        }

        int scan() throws IOException {
            if (index >= total) {
                index = 0;
                total = in.read(buf);
                if (total <= 0) {
                    return -1;
                }
            }
            return buf[index++];
        }

        String next() throws IOException {
            int c;
            for (c = scan(); c <= 32; c = scan());
            StringBuilder sb = new StringBuilder();
            for (; c > 32; c = scan()) {
                sb.append((char) c);
            }
            return sb.toString();
        }

        int nextInt() throws IOException {
            int c, val = 0;
            for (c = scan(); c <= 32; c = scan());
            boolean neg = c == '-';
            if (c == '-' || c == '+') {
                c = scan();
            }
            for (; c >= '0' && c <= '9'; c = scan()) {
                val = (val << 3) + (val << 1) + (c & 15);
            }
            return neg ? -val : val;
        }

        long nextLong() throws IOException {
            int c;
            long val = 0;
            for (c = scan(); c <= 32; c = scan());
            boolean neg = c == '-';
            if (c == '-' || c == '+') {
                c = scan();
            }
            for (; c >= '0' && c <= '9'; c = scan()) {
                val = (val << 3) + (val << 1) + (c & 15);
            }
            return neg ? -val : val;
        }
    }
}

import java.io.*;
import java.util.*;

public class Main {

	public static void main(String[] args) throws IOException {

		Scanner sc = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		long a = sc.nextLong();
		long b = sc.nextLong();
		if(b - a >= 10)out.print(0);
		else {
			int ans = 1;
			for(long i=a + 1; i<=b; i++) {
				ans = ((int)(i%10) * ans)%10;
			}
			out.print(ans);
		}
		out.close();
	}

	static class Scanner
	{
		StringTokenizer st;
		BufferedReader br;

		public Scanner(InputStream s){	br = new BufferedReader(new InputStreamReader(s));}

		public Scanner(String s) throws FileNotFoundException {	br = new BufferedReader(new FileReader(s));}

		public String next() throws IOException
		{
			while (st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine());
			return st.nextToken();
		}

		public int nextInt() throws IOException {return Integer.parseInt(next());}

		public long nextLong() throws IOException {return Long.parseLong(next());}

		public String nextLine() throws IOException {return br.readLine();}

		public double nextDouble() throws IOException { return Double.parseDouble(next()); }

		public boolean ready() throws IOException {return br.ready();}

	}
}

import java.io.*;
import java.util.*;

public class Main {

	public static void main(String[] args) throws IOException {

		Scanner sc = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		long a = sc.nextLong();
		long b = sc.nextLong();
		if(b - a >= 10)out.print(0);
		else {
			long ans = 1;
			for(long i=a + 1; i<=b; i++) {
				ans = (i%10 * ans)%10;
			}
			out.print(ans);
		}
		out.close();
	}

	static class Scanner
	{
		StringTokenizer st;
		BufferedReader br;

		public Scanner(InputStream s){	br = new BufferedReader(new InputStreamReader(s));}

		public Scanner(String s) throws FileNotFoundException {	br = new BufferedReader(new FileReader(s));}

		public String next() throws IOException
		{
			while (st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine());
			return st.nextToken();
		}

		public int nextInt() throws IOException {return Integer.parseInt(next());}

		public long nextLong() throws IOException {return Long.parseLong(next());}

		public String nextLine() throws IOException {return br.readLine();}

		public double nextDouble() throws IOException { return Double.parseDouble(next()); }

		public boolean ready() throws IOException {return br.ready();}

	}
}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class ProblemB {

	public static void main(String[] args) throws IOException{
		// TODO Auto-generated method stub
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String input[] = br.readLine().split(" ");
		long a = Long.parseLong(input[0]);
		long b = Long.parseLong(input[1]);
		long res = 1;
		for (long i = a + 1; i <= b; i++) {
			res = (res * (i % 10)) % 10;
			if (res == 0) break;
		}
		System.out.println(res);
	}

}

import java.io.*;
import java.util.*;

public class Main {
   private void solve() {
      long a = nextLong();
      long b = nextLong();
      if (b - a >= 10) out.println(0);
      else {
      	long ans = 1;
      	for (long i = a + 1; i <= b; i++) ans = (ans * (i % 10)) % 10;
      	out.println(ans);
      }
   }

   public static void main(String[] args) {
      new Main().run();
   }

   BufferedReader br;
   StringTokenizer st;
   PrintWriter out;

   private void run() {
      try {
         br = new BufferedReader(new InputStreamReader(System.in));
         out = new PrintWriter(System.out);
         // br = new BufferedReader(new FileReader("birthday.in"));
         // out = new PrintWriter(new FileWriter("birthday.out"));
         solve();
         br.close();
         out.close();
      } catch (IOException e) {
         e.printStackTrace();
      }
   }

   private long nextLong() {
   	return Long.parseLong(next());
   }

   private int nextInt() {
      return Integer.parseInt(next());
   }

   private String next() {
      while (st == null || !st.hasMoreTokens()) {
         try {
            st = new StringTokenizer(br.readLine());
         } catch (IOException e) {
            e.printStackTrace();
            return "END_OF_FILE";
         }
      }
      return st.nextToken();
   }
}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {

    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        InputReader in = new InputReader(inputStream);
        long a, b;
        a = in.nextLong();
        b = in.nextLong();
        long r = 1;
        for (long i = a + 1; i <= b; i++) {
            r *= (i % 10L);
            r %= 10L;
            if (r == 0L) break;
        }
        System.out.println(r);
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public long nextLong() {
            return Long.parseLong(next());
        }
    }
}

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args) throws Throwable
	{
		Scanner sc = new Scanner((System.in));
		long a = sc.nextLong() , b = sc.nextLong();
		if(a==b)
		{
			System.out.println(1);
			return;
		}
		long last = b-- % 100;
		BigInteger ten = new BigInteger(10+"");
		while(b > a && last != 0)
		{
			BigInteger tmp = new BigInteger(b+"");
			tmp = tmp.multiply(new BigInteger(last+""));
			last = Integer.parseInt(tmp.mod(ten).toString());
			last %= 10;
			b--;
		}

		System.out.println(last % 10);
	}

	static class Scanner
	{
		StringTokenizer st;
		BufferedReader br;
		public Scanner(InputStream s){	br = new BufferedReader(new InputStreamReader(s));}
		public Scanner(String s) throws FileNotFoundException {
			br = new BufferedReader(new FileReader(s));
		}
		public String next() throws IOException
		{
			while (st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine());
			return st.nextToken();
		}
		public int nextInt() throws IOException {return Integer.parseInt(next());}
		public String nextLine() throws IOException {return br.readLine();}
		public long nextLong() throws IOException {return Long.parseLong(next());}
		public double nextDouble() throws IOException {return Double.parseDouble(next());}
		public boolean ready() throws IOException {return br.ready();}
	}
}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {

    public static void main(String[] args) throws IOException {
        FastReader in = new FastReader();
        long a, b;
        a = in.nextLong();
        b = in.nextLong();
        long r = 1;
        for (long i = a + 1; i <= b; i++) {
            r *= (i % 10L);
            r %= 10L;
            if (r == 0L) break;
        }
        System.out.println(r);
    }

    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }
}

import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.math.BigInteger;

public class Main {

    public static void main(String[] args) throws IOException {
        Reader in = new Reader();
        long a, b;
        a = in.nextLong();
        b = in.nextLong();
        long r = 1;
        for (long i = a + 1; i <= b; i++) {
            r *= (i % 10L);
            r %= 10L;
            if (r == 0L) break;
        }
        System.out.println(r);
    }

    public static BigInteger factorial(long n) {
        BigInteger result = BigInteger.ONE;
        for (; n > 1; n--) {
            result = result.multiply(BigInteger.valueOf(n));
        }
        return result;
    }

    static class Reader {
        final private int BUFFER_SIZE = 1 << 16;
        private DataInputStream din;
        private byte[] buffer;
        private int bufferPointer, bytesRead;

        public Reader() {
            din = new DataInputStream(System.in);
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public Reader(String file_name) throws IOException {
            din = new DataInputStream(new FileInputStream(file_name));
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public String readLine() throws IOException {
            byte[] buf = new byte[64]; // line length
            int cnt = 0, c;
            while ((c = read()) != -1) {
                if (c == '\n')
                    break;
                buf[cnt++] = (byte) c;
            }
            return new String(buf, 0, cnt);
        }

        public int nextInt() throws IOException {
            int ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            } while ((c = read()) >= '0' && c <= '9');

            if (neg)
                return -ret;
            return ret;
        }

        public long nextLong() throws IOException {
            long ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }

        public double nextDouble() throws IOException {
            double ret = 0, div = 1;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();

            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');

            if (c == '.') {
                while ((c = read()) >= '0' && c <= '9') {
                    ret += (c - '0') / (div *= 10);
                }
            }

            if (neg)
                return -ret;
            return ret;
        }

        private void fillBuffer() throws IOException {
            bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
            if (bytesRead == -1)
                buffer[0] = -1;
        }

        private byte read() throws IOException {
            if (bufferPointer == bytesRead)
                fillBuffer();
            return buffer[bufferPointer++];
        }

        public void close() throws IOException {
            if (din == null)
                return;
            din.close();
        }
    }
}

import java.io.*;
import java.util.*;

public class Main {
    private void solve() {
        long a = nextLong();
        long b = nextLong();
        int proizv = 1;
        for (long i = a+1; i <= b; i++) {
            proizv*=(i%10);
            proizv%=10;
            if(proizv == 0)break;
        }
        System.out.println(proizv);
        //Идём от а до b берём последнюю цифру и
        //её умножаем с следующей и снова первую от произведения берём тока
    }
/*    private boolean isPrime(long n) {
        for (long i = 2; i <= Math.sqrt(n); i++) {
            if(n%i==0)return false;
        }
        return true;
    }*/

    public static void main(String[] args) {
        new Main().run();
    }

    BufferedReader br;
    StringTokenizer st;
    PrintWriter out;

    private void run() {
        try {
            br = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
//            br = new BufferedReader(new FileReader("input.txt"));
//            out = new PrintWriter(new FileWriter("output.txt"));
            solve();
            br.close();
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private long nextLong() {return Long.parseLong(next()); }

    private int nextInt() {
        return Integer.parseInt(next());
    }

    private String next() {
        while (st == null || !st.hasMoreTokens()) {
            try {
                st = new StringTokenizer(br.readLine());
            } catch (IOException e) {
                e.printStackTrace();
                return "END_OF_FILE";
            }
        }
        return st.nextToken();
    }
}

import java.util.*;
public class Main{
public static void main(String[] args){

Scanner scan=new Scanner(System.in);
long a=scan.nextLong();
long b=scan.nextLong();

if(b<a){System.out.println("0");}

if(b==a){
	System.out.println("1");
}
if(b>a){

	if(b-a>=5){
		System.out.println("0");
	}else{

		long multiply=1;
	for(long i=a+1;i<=b;i++){
		multiply=multiply*(i%10);

	}

	System.out.println(multiply%10);

	}

}

}
}

import java.util.Arrays;
import java.util.Scanner;

public class Tako {
	public static void main(String[] args){

		Scanner s = new Scanner(System.in);

		long x = s.nextLong();
		long y = s.nextLong();

		if(x==y){
			System.out.println("1");
		}

		else if(y-x>=5)
			System.out.println("0");
		else{
			long ans = y%10;
			long z = y-x;
			for (int i = 1; i < z; i++) {
				 ans = (ans * (y-i))%10;
			}
			System.out.println(ans%10);
		}
	}
}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.StringTokenizer;

public class ProblemB {

	static Scanner sc = new Scanner(System.in);
	static PrintWriter pw = new PrintWriter(System.out);

	static BigInteger perm(long n, long r) {
		BigInteger ans = new BigInteger(n + "");
		for (long i = n - 1, j = r - 1; j > 0; i--, j--) {
			ans = ans.multiply(new BigInteger(i + ""));
		}
//		 System.out.println(ans);
		return ans;
	}

	// 99999999999999997 99999999999999999
	public static void main(String[] args) throws IOException {

		long small = sc.nextLong(), big = sc.nextLong();
		if (small == 0)
			small = 1;
		if (big == 0)
			big = 1;
		if (big == small) {
			System.out.println(1);
		} else {
			long diff = big - small;
			if (diff > 10) {
				System.out.println(0);
				return;
			}
			String s = perm(big, diff).toString();
			System.out.println(s.charAt(s.length() - 1));
		}
		pw.flush();
	}

	static class Scanner {
		StringTokenizer st;
		BufferedReader br;

		public Scanner(InputStream s) {
			br = new BufferedReader(new InputStreamReader(s));
		}

		public String next() throws IOException {
			while (st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine());
			return st.nextToken();
		}

		public int nextInt() throws IOException {
			return Integer.parseInt(next());
		}

		public long nextLong() throws IOException {
			return Long.parseLong(next());
		}
	}

}

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Pradyumn
 */
public class Progra {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        FastReader in = new FastReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskB solver = new TaskB();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskB {
        public void solve(int testNumber, FastReader in, PrintWriter out) {
            long a = in.nextLong();
            long b = in.nextLong();
            if (b - a >= 10) {
                out.println(0);
            } else {
                long ans = 1;
                for (long x = a + 1; x <= b; x++) {
                    ans = ans * (x % 10) % 10;
                }
                out.println(ans);
            }
        }

    }

    static class FastReader {
        private InputStream stream;
        private byte[] buf = new byte[8192];
        private int curChar;
        private int pnumChars;
        private FastReader.SpaceCharFilter filter;

        public FastReader(InputStream stream) {
            this.stream = stream;
        }

        private int pread() {
            if (pnumChars == -1) {
                throw new InputMismatchException();
            }
            if (curChar >= pnumChars) {
                curChar = 0;
                try {
                    pnumChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (pnumChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar++];
        }

        public long nextLong() {
            int c = pread();
            while (isSpaceChar(c))
                c = pread();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = pread();
            }
            long res = 0;
            do {
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = pread();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        private boolean isSpaceChar(int c) {
            if (filter != null) {
                return filter.isSpaceChar(c);
            }
            return isWhitespace(c);
        }

        private static boolean isWhitespace(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        private interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        }

    }
}

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong(), b = sc.nextLong();
        int output = (int)((a + 1) % 10);
        int temp = output + 1;

        for (int i = 0 ; i < b - a - 1 ; i ++) {
            output = (output * temp) % 10;
            temp ++;
            if (output == 0) {
                break;
            }
        }
        if (a == b) {
            output = 1;
        }
        System.out.println(output);
    }
}

import java.util.*;
import java.io.*;
import java.math.*;
import java.util.LinkedList;

    public  class Sample implements Runnable
    {

          public static void solve()
          {
            long a=l();
            long b=l();
            long num=b-a;
            if(num==0){
              out.println("1");
              return;
            }

            long ans=b%10;
            if(num>=5)
            {
              out.println("0");
              return;
             }
            else
            {

              for(int i=1;i<num;i++)
              { b--;
                ans=((ans)*((b)%10))%10;
              }
            }
            out.println(ans);
     }
          static void khojo(long[] a,HashMap hs,int i,int n,long res)
          {
            if(i>=n)
            {
              if(hs.containsKey(res))
              {
                hs.put(res,(long)hs.get(res)+1L);
              }
              else
              {
                hs.put(res,1L);
              }
            }
            else
            {
              khojo(a,hs,i+1,n,(res^a[i]));
              khojo(a,hs,i+1,n,res);
          }
          }

          public void run()
          {
              solve();
              out.close();
          }

          public static void main(String[] args) throws IOException
          {
                new Thread(null, new Sample(), "whatever", 1<<26).start();
          }
         static class Pair implements Comparable<Pair>
         {
            long a;
            int b;
            Pair(){}
            Pair(long a,int b)
            {
                       this.a=a;
                       this.b=b;
            }

            public int compareTo(Pair x)
           {
                return Long.compare(x.a,this.a);
           }
        }

    ////////////////////////////////////////////////////// Merge Sort ////////////////////////////////////////////////////////////////////////

   static class Merge
   {

        public static void sort(long inputArr[])
        {
            int length = inputArr.length;
            doMergeSort(inputArr,0, length - 1);
        }

        private static void doMergeSort(long[] arr,int lowerIndex, int higherIndex)
        {
            if (lowerIndex < higherIndex) {
                int middle = lowerIndex + (higherIndex - lowerIndex) / 2;
                doMergeSort(arr,lowerIndex, middle);
                doMergeSort(arr,middle + 1, higherIndex);
                mergeParts(arr,lowerIndex, middle, higherIndex);
            }
        }

        private static void mergeParts(long[]array,int lowerIndex, int middle, int higherIndex)
        {
            long[] temp=new long[higherIndex-lowerIndex+1];
            for (int i = lowerIndex; i <= higherIndex; i++)
            {
                temp[i-lowerIndex] = array[i];
            }
            int i = lowerIndex;
            int j = middle + 1;
            int k = lowerIndex;
            while (i <= middle && j <= higherIndex)
            {
                if (temp[i-lowerIndex] < temp[j-lowerIndex])
                {
                    array[k] = temp[i-lowerIndex];
                    i++;
                } else {
                    array[k] = temp[j-lowerIndex];
                    j++;
                }
                k++;
            }
            while (i <= middle)
            {
                array[k] = temp[i-lowerIndex];
                k++;
                i++;
            }
            while(j<=higherIndex)
            {
                array[k]=temp[j-lowerIndex];
                k++;
                j++;
            }
        }

    }

    /////////////////////////////////////////////////////////// Methods ////////////////////////////////////////////////////////////////////////

     static boolean isPal(String s)
     {
        for(int i=0, j=s.length()-1;i<=j;i++,j--)
        {
                if(s.charAt(i)!=s.charAt(j)) return false;
        }
        return true;
     }
     static String rev(String s)
     {
                StringBuilder sb=new StringBuilder(s);
                sb.reverse();
                return sb.toString();
     }
     static int gcd(int a,int b){return (a==0)?b:gcd(b%a,a);}
     static long gcdExtended(long a,long b,long[] x)
     {

        if(a==0){
            x[0]=0;
            x[1]=1;
            return b;
        }
        long[] y=new long[2];
        long gcd=gcdExtended(b%a, a, y);

        x[0]=y[1]-(b/a)*y[0];
        x[1]=y[0];

        return gcd;
    }

     boolean findSum(int set[], int n, long sum)
    {
      if (sum == 0)
         return true;
      if (n == 0 && sum != 0)
         return false;
      if (set[n-1] > sum)
         return findSum(set, n-1, sum);
      return findSum(set, n-1, sum) ||findSum(set, n-1, sum-set[n-1]);
    }

      public static long modPow(long base, long exp, long mod)
     {
        base = base % mod;
        long result = 1;
        while (exp > 0)
       {
            if (exp % 2 == 1)
            {
                result = (result * base) % mod;
            }
            base = (base * base) % mod;
            exp = exp >> 1;
       }
        return result;
    }

    static long[] fac;
    static long[] inv;
    static long mod=(long)1e9+7;
    public static void cal()
    {
        fac = new long[1000005];
        inv = new long[1000005];
        fac[0] = 1;
        inv[0] = 1;
        for (int i = 1; i <= 1000000; i++)
        {
            fac[i] = (fac[i - 1] * i) % mod;
            inv[i] = (inv[i - 1] * modPow(i, mod - 2, mod)) % mod;
        }
    }

    public static long ncr(int n, int r)
    {
        return (((fac[n] * inv[r]) % mod) * inv[n - r]) % mod;
    }

////////////////////////////////////////// Input Reader ////////////////////////////////////////////////////////////////////////////////////////////////////

    static InputReader sc = new InputReader(System.in);
    static PrintWriter out= new PrintWriter(System.out);

    static class InputReader {

          private final InputStream stream;
          private final byte[] buf = new byte[8192];
          private int curChar, snumChars;
          private SpaceCharFilter filter;

          public InputReader(InputStream stream) {
                  this.stream = stream;
          }

          public int snext()
         {
                  if (snumChars == -1)
                          throw new InputMismatchException();
                  if (curChar >= snumChars) {
                          curChar = 0;
                          try {
                                  snumChars = stream.read(buf);
                          } catch (IOException e) {
                                  throw new InputMismatchException();
                          }
                          if (snumChars <= 0)
                                  return -1;
                  }
                  return buf[curChar++];
          }

          public int nextInt()
         {
                  int c = snext();
                  while (isSpaceChar(c))
                  {
                          c = snext();
                  }
                  int sgn = 1;
                  if (c == '-')
                  {
                          sgn = -1;
                          c = snext();
                  }
                  int res = 0;
                  do {
                          if (c < '0' || c > '9')
                                  throw new InputMismatchException();
                          res *= 10;
                          res += c - '0';
                          c = snext();
                  } while (!isSpaceChar(c));
                  return res * sgn;
          }

          public long nextLong()
          {
                  int c = snext();
                  while (isSpaceChar(c))
                  {
                          c = snext();
                  }
                  int sgn = 1;
                  if (c == '-')
                  {
                          sgn = -1;
                          c = snext();
                  }
                  long res = 0;
                  do {
                          if (c < '0' || c > '9')
                                  throw new InputMismatchException();
                          res *= 10;
                          res += c - '0';
                          c = snext();
                  } while (!isSpaceChar(c));
                  return res * sgn;
          }

          public int[] nextIntArray(int n)
          {
                  int a[] = new int[n];
                  for (int i = 0; i < n; i++)
                  {
                          a[i] = nextInt();
                  }
                  return a;
          }

          public long[] nextLongArray(int n)
          {
                  long a[] = new long[n];
                  for (int i = 0; i < n; i++)
                  {
                          a[i] = nextLong();
                  }
                  return a;
          }

          public String nextLine()
         {
                  int c = snext();
                  while (isSpaceChar(c))
                          c = snext();
                  StringBuilder res = new StringBuilder();
                  do {
                          res.appendCodePoint(c);
                          c = snext();
                  } while (!isEndOfLine(c));
                  return res.toString();
          }

          public boolean isSpaceChar(int c)
          {
                  if (filter != null)
                          return filter.isSpaceChar(c);
                  return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
          }

          private boolean isEndOfLine(int c)
          {
                  return c == '\n' || c == '\r' || c == -1;
          }

          public interface SpaceCharFilter
          {
                  public boolean isSpaceChar(int ch);
          }

    }

    static int i()
    {
        return sc.nextInt();
    }
    static long l(){
        return sc.nextLong();
    }
    static int[] iarr(int n)
    {
        return sc.nextIntArray(n);
    }
    static long[] larr(int n)
    {
        return sc.nextLongArray(n);
    }
    static String s(){
        return sc.nextLine();
    }

 }

import java.util.*;
public class Q869B
{
	public static void main(String dfg[])
	{
		Scanner sc=new Scanner(System.in);
		long a=sc.nextLong();
		long b=sc.nextLong();
		long c=b-a;
		long d=b%10;long f=1;
		if(c==0)
		{
			System.out.println(1);
		}
		else if(d==0)
		{
		System.out.println(0);
		}
		else
		{
		for(int x=0;x<c;x++)
		{
			f=f*d--;
			if(f%10==0)
			{
			break;
			}

		}
		System.out.println(f%10);
		}
	}
	}

import java.util.*;
public class The_Eternal_Immortality
{
	public static void main(String ar[])
	{
		Scanner s1 = new Scanner(System.in);
		long a,b;
		a = s1.nextLong();
		b = s1.nextLong();
		if(a == 0 && b!=0)
		{
			if(b>=5)
				System.out.println("0");
			else if(b == 3)
				System.out.println("6");
			else
				System.out.println(b);
		}
		else if(b-a == 1)
			System.out.println(b%10);
		else if(a == b)
			System.out.println("1");
		else if(b-a>=5)
			System.out.println("0");
		else
		{
			int mul = 1;
			for(long i=a+1;i<=b;i++)
			{
				//System.out.println("i: "+i);
				if(i%5==0)
				{
					System.out.println("0");
					return;
				}
				mul *= (i%10);
			}
			System.out.println(mul%10);
		}
		s1.close();
	}
}

import java.util.*;
import java.math.*;
public class TheEternalImmortality {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong(), b = sc.nextLong();
		long r=1;

			for(long i=a+1; i<=b; i++)
			{
				r = r*(i%10);
				if(r == 0)
					break;
			}

		System.out.println(r%10);
	}

}

import java.math.BigInteger;
import java.util.Scanner;

public class reg {
    public static void main(String[] args) {
        Scanner ob = new Scanner(System.in);
        Long a=ob.nextLong();
        Long b=ob.nextLong();
        BigInteger result=new BigInteger("1");
        if(b-a>=10)
            System.out.println("0");
        else if(a==1||a==0)
        {
            for(long i=2;i<=b;i++)
            {
                result=result.multiply(BigInteger.valueOf(i));
            }
            System.out.println(result.mod(BigInteger.valueOf(10)));
        }
        else
        {
            long offset=b-a;
            for(long i=1;i<=offset;i++)
                result=result.multiply(BigInteger.valueOf(a+i));
            System.out.println(result.mod(BigInteger.valueOf(10)));
        }
    }}

//package codeForces.contests.codeforcesRound439Div2;

import java.math.BigInteger;
import java.util.Scanner;

/**
 * Created by vladix on 10/8/17.
 */
public class problemB {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        BigInteger a = new BigInteger(in.next() + "");
        BigInteger b = new BigInteger(in.next() + "");

        BigInteger subtract = b.subtract(a);

        if (a.equals(b)) {
            System.out.println("1");
        } else if (subtract.compareTo(new BigInteger("5")) >= 0) {
            System.out.println("0");
        } else {
            int iterations = Integer.parseInt(subtract.toString());
            BigInteger result = a.add(BigInteger.ONE);
            for (int i = 0; i < iterations - 1; i++) {
                result = result.multiply(a.add(new BigInteger((i + 2) + "")));
            }

            System.out.println(result.toString().charAt(result.toString().length() - 1));
        }
    }
}

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.StringTokenizer;

public class df {
	public static void main(String[] args) throws Exception {
		BufferedReader in = new BufferedReader (new InputStreamReader (System.in));
		PrintWriter out = new PrintWriter(System.out);
		StringTokenizer toks= new StringTokenizer(in.readLine());
		long a =Long.parseLong(toks.nextToken());
		long b =Long.parseLong(toks.nextToken());
		int c =1;
//		for (int i = 1; i <= a; i++) {
////			out.println(c);
//			c=((c%10)*(i%10))%10;
//		}
		long k=1;
			for (long i = a+1; i <= b; i++) {
				k=((k%10)*(i%10))%10;
				if(k==0)
					i=b;
//				out.println(k);

		}
		out.print(k);
		out.close();
	}
}

import java.math.BigInteger;
import java.util.Scanner;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args) {

		long  a,b;

		Scanner sc = new Scanner(System.in);
		while(sc.hasNextLine()) {

			StringTokenizer line = new StringTokenizer(sc.nextLine());
			a = Long.parseLong(line.nextToken());
			b = Long.parseLong(line.nextToken());

			if(a==b) {System.out.println(1);}
			else if(b-a==1){
				String s = Long.toString(b);
				System.out.println(s.charAt(s.length()-1));

			}

			else {

				String str = Long.toString(b);
				int i =Character.getNumericValue(str.charAt(str.length()-1));
				long counter = b-a-1;

				if(i-counter<=0) {System.out.println(0);}
				else {

				b=i;

					long helper, result = b ;

					for(;counter>0;counter--) {

						helper = b - 1;

						result = result * helper;
						b--;

						}

					String s = Long.toString(result);
					System.out.println(s.charAt(s.length()-1));

				}

				//String s = result.toString();

			}

		}

	}

}

import java.io.PrintWriter;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.Scanner;
import java.util.*;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.BufferedWriter;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.OutputStreamWriter;
import java.util.InputMismatchException;
import jdk.nashorn.internal.codegen.CompilerConstants;
import java.math.BigInteger;

public class Solution{
    public static void
         main(String [] args)throws IOException{

        Scanner sc=new Scanner(System.in);
         //BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
           long a=sc.nextLong();
           long b=sc.nextLong();

           long mul=1;
           for(long i=a+1;i<=b;i++){
               long tem=i%10;
               mul=mul*tem;

               if(mul==0)break;

           }
           System.out.println(mul%10);

         }

}

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class CF869B {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		SolutionCF869B sl = new SolutionCF869B();
		BigInteger a = sc.nextBigInteger();
		BigInteger b = sc.nextBigInteger();
		sl.solve(a, b);

	}
}

class SolutionCF869B {
	public void solve(BigInteger a, BigInteger b) {
		BigInteger c = b.subtract(a);
		if (c.compareTo(new BigInteger("4")) == 1) {
			System.out.println("0");
		} else {
			BigInteger d = BigInteger.ONE;
			for (int i = 1; i <= c.intValue(); i++) {
				d = d.multiply(a.add(new BigInteger(i + "")));
			}
			String out = d.toString();
			System.out.println(out.charAt(out.length() - 1));
		}
	}
}

import java.io.*;
import java.util.*;

public class force{
	public static void main(String args[]){
		Scanner in=new Scanner(System.in);
		long a,b,i,j,f=1;
		a=in.nextLong();
		b=in.nextLong();
		long z=b%10;
		if(a==b)
			f=1;
		else if(z==5&&a%10==4)
				f=5;
		else if((z>5&&(a%10<5))||z==0){
			f=0;
		}
		else if(z<5&&(a%10)<0)
			f=0;
		else if(z==5&&(a%10)<4)
			f=0;
		else if(a<b){
			for(i=b;i>a;i--){
				j=i%10;
				f=(f*j)%10;
				if(f==0||f==5&&(i-1)%2==0){
					f=0;
					break;
				}

			}
		}
		System.out.println(f);

	}
}

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
import java.io.*;
import java.util.*;
/**
 *
 * @author rahman
 */
public class B869 {
    public static void main(String[] args)throws IOException{
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        long b= sc.nextLong();
        if(b==a){
            System.out.println(5/5);
        }
        else{boolean flag = false;
        long prod = 1;
        for(long i = a+1; i<=b; i++){
//            System.out.println("initial "+i);
//            i=i%10;
               long v = i%10;
            //System.out.println("v "+v);
            //i = i%10;
            //System.out.println(i+" i");
            prod = prod * v;
            prod = prod%10;
            //prod = prod%10;
            //System.out.println("prod "+prod);
            if(prod == 0){
                flag = true;
                break;
            }
        }
        if(flag){
            System.out.println(0);
        }
        else{
            System.out.println(prod%10);
        }
        }
    }
}

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()) {
            long a = sc.nextLong();
            long b = sc.nextLong();
            if(b-a>10 || a>b) {
                System.out.println("0");
            } else {
                Long tmp = 1L;
                a = a %1000;b=b%1000;
                if(a==0 && b==0)
                    System.out.println("1");
                else{
                    if(b==0) b=1000;
                    while (a<b){

                        a = a+1;
//                    if(a%10==0) continue;
                        tmp = tmp * (a) % 100;
                    }
                    System.out.println(tmp%10);
                }

            }
        }
    }
}

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.util.Scanner;

/**
 * Created by fengp on 10/10/17.
 */
public class CF869B {
    public static int solve(long a, long b){
        if (b-a>=5)return 0;
        int ans=1;
        for (long c=a+1;c<=b;++c){
            ans*=(c%10);
        }
        return ans%10 ;
    }

    public static void main(String[] args) {

        InputStream input = System.in;
        PrintStream output = System.out;
        if (args.length == 2) {
            try {
                input = CF869B.class.getClassLoader().getResourceAsStream(args[0]);
                output = new PrintStream(args[1]);
            } catch (IOException e) {
                e.printStackTrace();
                return;
            }
        }
        Scanner in = new Scanner(input);
        while (in.hasNextLong()) {
            long a;
            a = in.nextLong();
            long b;
            b = in.nextLong();
            output.println(String.format("%d", solve(a,b)));
        }
    }
}

import java.util.Scanner;

public class sss {
	 static Scanner read=new Scanner(System.in);

	public static void main(String[] args) {

String a=read.next();
String  b=read.next();
int A;
int B;
int A1=0;
int B1=0;
if (a.length()>=10){
 A=Integer.parseInt(a.substring(a.length()-9 , a.length()));
 A1=Integer.parseInt(a.substring(0 , a.length()-9));
}
else {A=Integer.parseInt(a);
if (A==0) A=1;
}
if (b.length()>=10){
	 B=Integer.parseInt(b.substring(b.length()-9 , b.length()));
	 B1=Integer.parseInt(b.substring(0 , b.length()-9));
	}
	else {
		B=Integer.parseInt(b);
		if (B==0) B=1;
	}

int s=1;
if (A==B && A1==B1) System.out.println(s);
else{
if (B-A-1 >= 10 || A==0 || B==0 || B1-A1>=1) s=0;
else{
for(int i=A+1;i<=B;i++){
	s=s*(i%10);
if (s>=10) s=s%10;

}
}
System.out.println(s);
}
	}}

import java.io.*;
import java.util.*;
public class eternal
{
    public static void main(String args[])throws IOException
    {
        Scanner in = new Scanner(System.in);
        long a , b ;
        a=in.nextLong();
        b=in.nextLong();
        long  fb=1 ;
       if(b-a>10)
            System.out.println("0");
       else
       {
        for(long i=a+1;i<=b;i++)

           fb=((fb%10)*(i%10))%10;

           System.out.println((int)(fb));
       }

    }
}

import java.util.*;
import java.io.*;
import java.math.*;
public class mmm
{
    static class InputReader {
        public BufferedReader br;
        public StringTokenizer token;
        public InputReader(InputStream stream)
        {
            br=new BufferedReader(new InputStreamReader(stream),32768);
            token=null;
        }

        public String next()
        {
            while(token==null || !token.hasMoreTokens())
            {
                try
                {
                    token=new StringTokenizer(br.readLine());
                }
                catch(IOException e)
                {
                    throw new RuntimeException(e);
                }
            }
            return token.nextToken();
        }

        public int nextInt()
        {
            return Integer.parseInt(next());
        }

        public long nextLong()
        {
            return Long.parseLong(next());
        }
    }
    /*static class card{
    long up;
    int down;
    public card(long u,int d)
    {
    this.up=u;
    this.down=d;
    }
    }
    static class sort implements Comparator<card>
    {
    public int compare(card o1,card o2)
    {
    if(o1.up!=o2.up)
    return (int)(o1.up-o2.up);
    else
    return (int)(o1.down-o2.down);
    }
    }
    static void shuffle(long a[])
    {
    List<Long> l=new ArrayList<>();
    for(int i=0;i<a.length;i++)
    l.add(a[i]);
    Collections.shuffle(l);
    for(int i=0;i<a.length;i++)
    a[i]=l.get(i);
    }

    static long gcd(long a,long b)
    {
    if(b==0)
    return a;
    else
    return gcd(b,a%b);
    }
    static int ans1=Integer.MAX_VALUE,ans2=Integer.MAX_VALUE,ans3=Integer.MAX_VALUE,ans4=Integer.MAX_VALUE;
    static boolean v[]=new boolean[101];
    static void dfs(Integer so,Set<Integer> s[]){
    if(!v[so.intValue()])
    {
    v[so]=true;
    for(Integer h:s[so.intValue()])
    {
    if(!v[h.intValue()])
    dfs(h,s);
    }
    }
    }
    static class Print{
    public PrintWriter out;
    Print(OutputStream o)
    {
    out=new PrintWriter(o);
    }
    }
    static int CeilIndex(int A[], int l, int r, int key)
    {
    while (r - l > 1) {
    int m = l + (r - l) / 2;
    if (A[m] >= key)
    r = m;
    else
    l = m;
    }

    return r;
    }

    static int LongestIncreasingSubsequenceLength(int A[], int size)
    {
    // Add boundary case, when array size is one
    int[] tailTable = new int[size];
    int len; // always points empty slot
    tailTable[0] = A[0];
    len = 1;
    for (int i = 1; i < size; i++) {
    if (A[i] < tailTable[0])
    // new smallest value
    tailTable[0] = A[i];

    else if (A[i] > tailTable[len - 1])
    // A[i] wants to extend largest subsequence
    tailTable[len++] = A[i];

    else
    // A[i] wants to be current end candidate of an existing
    // subsequence. It will replace ceil value in tailTable
    tailTable[CeilIndex(tailTable, -1, len - 1, A[i])] = A[i];
    }
    return len;
    }*/
    /*static int binary(int n)
    {
    int s=1;
    while(n>0)
    {
    s=s<<1;
    n--;
    }
    return s-1;
    }
    static StringBuilder bin(int i,int n)
    {
    StringBuilder s=new StringBuilder();
    while(i>0)
    {
    s.append(i%2);
    i=i/2;
    }
    while(s.length()!=n)
    {
    s.append(0);
    }
    return s.reverse();
    }*/
    public static void main(String args[])
    {
        InputReader sc=new InputReader(System.in);
        String s1=sc.next();
        String s2=sc.next();
        long a=Long.parseLong(s1);
        long b=Long.parseLong(s2);
        if(b-a==1)
        System.out.println(b);
        else
        {
            BigInteger pro=BigInteger.ONE;
            int f=0;
            for(long i=b;i>a;i--)
            {
                if(i%10==0)
                {
                    System.out.println(0);
                    System.exit(0);
                }
                else if(i%2==0)
                {
                    if(f==0)
                    f=1;
                    else
                    {
                         System.out.println(0);
                         System.exit(0);
                    }
                }
                else if(i%5==0)
                {
                    if(f==0)
                    f=1;
                    else
                    {
                         System.out.println(0);
                         System.exit(0);
                    }
                }
                pro=pro.multiply(BigInteger.valueOf(i));
            }
            //System.out.println(pro);
            String p=pro.toString();
            System.out.println(p.charAt(p.length()-1));
        }
    }
}

import java.util.*;
import java.io.*;

public class Main {
  public static void main (String[] args) {
    Scanner sc = new Scanner(System.in);
    //BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    OutputStream out = new BufferedOutputStream ( System.out );
    String n = sc.next();
    String m = sc.next();
    int a = Integer.parseInt("" + n.charAt(n.length()-1));
    int b = Integer.parseInt("" + m.charAt(m.length()-1));
    int ans = -1;
    if(a > b) {
      ans = 0;
    }
    else {
      int temp = 1;
      for(int i = b; i > a; i--) {
        temp *= i;
      }
      ans = temp % 10;
    }
    System.out.println(ans);
  }
}

import java.math.BigInteger;
import java.util.*;
import java.util.stream.IntStream;
import java.util.stream.Stream;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        long a = in.nextInt();
        long b = in.nextInt();

        long start = a + 1;
        if (start % 10 == 1 && b % 10 == 2 || start % 10 == 3 && b % 10 == 4 || start % 10 == 6 && b % 10 == 7
                || start % 10 == 8 && b % 10 == 9) {
            System.out.println(2);
        } else if ((start % 10 == 1 || start % 10 == 2) && b % 10 == 3) {
            System.out.println(6);
        } else if ((start % 10 == 1 || start % 10 == 2) && b % 10 == 4) {
            System.out.println(4);
        }  else {
            System.out.println(0);
        }
    }
}

import java.util.*;

public class Immortality {
	public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int x = 0;

        int a = sc.nextInt();
        int b = sc.nextInt();

        int aFact = factorial(a);
        int bFact = factorial(b);

        x = (bFact/aFact) % 10;

        System.out.println(x);

    }

    public static int factorial(int y){
        int fact = 1;
        for(int i=1;i<=y;i++){
            fact=(fact % 10) * (i % 10);
            if(fact % 10 == 0){
                break;
            }
        }
        return fact;

     }

}

import java.util.Scanner;

public class HelloWorld{

     public static void main(String []args){
        Scanner input = new Scanner(System.in);
        int a = input.nextInt();
        int b = input.nextInt();

        if(a == 0 && b > 4){
            System.out.println("0");
        }else{
            System.out.println(fact(a,b));
        }

     }
     public static int fact(int a, int b){
         int diff = b - a;
         int x = (b - diff) + 1;
         int result = 1;
         for(int i = x; i <= b; i++){
             result = result * i;
         }
         return result % 10;

     }
}

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.StringTokenizer;

public class df {
	public static void main(String[] args) throws Exception {
		BufferedReader in = new BufferedReader (new InputStreamReader (System.in));
		PrintWriter out = new PrintWriter(System.out);
		StringTokenizer toks= new StringTokenizer(in.readLine());
		long a =Long.parseLong(toks.nextToken());
		long b =Long.parseLong(toks.nextToken());
		int c =1;
//		for (int i = 1; i <= a; i++) {
////			out.println(c);
//			c=((c%10)*(i%10))%10;
//		}
		long k=1;
			for (long i = a+1; i <= b; i++) {
				k=((k%10)*(i%10))%10;
				out.println(k);

		}
//		out.print(k);
		out.close();
	}
}

/*
 * Remember a 2.0 student can know more than a 4.0 student.
 * Grades don't determine intelligence, they test obedience.
 * I Never Give Up.
 */
import java.util.*;
import java.io.*;

import static java.lang.System.out;
import static java.lang.Math.pow;
//import static java.lang.Math.sqrt;
//import static java.lang.Math.ceil;
//import static java.lang.Math.abs;
//import static java.lang.Math.min;
//import static java.lang.Math.max;
public class ContestMain {
	private static long MOD=1000000007;//10^9+7
	private static final int N=(int) 2e5+5; //200005
	private static Scanner in=new Scanner(System.in);
	private static BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
	private static ArrayList<Integer> v[]=new ArrayList[N];
	private static boolean mark[]=new boolean[N];
	static int choice=Integer.MAX_VALUE,trav=Integer.MAX_VALUE;

	public static void main(String[] args) throws IOException{
		long s=in.nextLong();
		long n=in.nextLong();
		double res=pow((double)(n/2.71828),n)/pow((double)(s/2.71828),s);
		if(s!=0)res=(Math.sqrt(n)/Math.sqrt(s))*res;
		else if(n<5){
			long mult=1;
			for(int i=1;i<=n;i++)
				mult*=i;
			res=mult;
		}
		else res=0;
		long final_res=(long)res;
		String p=""+final_res;
		out.println(p.charAt(p.length()-1));
	}
}

import java.math.BigInteger;
import java.util.Scanner;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args) {

		long  a,b;

		Scanner sc = new Scanner(System.in);
		while(sc.hasNextLine()) {

			StringTokenizer line = new StringTokenizer(sc.nextLine());
			a = Long.parseLong(line.nextToken());
			b = Long.parseLong(line.nextToken());

			if(a==b) {System.out.println(1);}
			else if(b-a==1){System.out.println(b);}

			else {

				String str = Long.toString(b);
				int i =Character.getNumericValue(str.charAt(str.length()-1));
				long counter = b-a-1;

				if(i-counter<=0) {System.out.println(0);}
				else {

				b=i;

					long helper, result = b ;

					for(;counter>0;counter--) {

						helper = b - 1;

						result = result * helper;
						b--;

						}

					String s = Long.toString(result);
					System.out.println(s.charAt(s.length()-1));

				}

				//String s = result.toString();

			}

		}

	}

}

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskB solver = new TaskB();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskB {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            long a = in.nextLong();
            long b = in.nextLong();

            if (b - a > 10) {
                out.println(0);
                return;
            }

            if (b % 10 == 0 || (a + 1) % 10 == 0) {
                out.println(0);
                return;
            }

            long ans = 1;
            for (long temp = a + 1; temp <= b; ++temp) {
                String req = Long.toString(temp);
                int len = req.length();
                ans *= req.charAt(len - 1) - '0';
            }
            String ansToStr = Long.toString(ans);
            out.println(ansToStr.charAt(ansToStr.length() - 1));
        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private InputReader.SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1) {
                throw new InputMismatchException();
            }
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar++];
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;
            do {
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public boolean isSpaceChar(int c) {
            if (filter != null) {
                return filter.isSpaceChar(c);
            }
            return isWhitespace(c);
        }

        public static boolean isWhitespace(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        }

    }
}

import java.util.*;

public class Main2 {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        long a = in.nextLong();
        long b = in.nextLong();

        long f = 1;
        for (long e = a + 1; e <= b; e++) {
            f *= e;
            if (f % 10 == 0) {
                System.out.print(0);
                return;
            }
        }

        System.out.print(f % 10);
    }
}

/*
 * Remember a 2.0 student can know more than a 4.0 student.
 * Grades don't determine intelligence, they test obedience.
 * I Never Give Up.
 */
import java.util.*;
import java.io.*;

import static java.lang.System.out;
import static java.lang.Math.pow;
//import static java.lang.Math.sqrt;
//import static java.lang.Math.ceil;
//import static java.lang.Math.abs;
//import static java.lang.Math.min;
//import static java.lang.Math.max;
public class ContestMain {
	private static long MOD=1000000007;//10^9+7
	private static final int N=(int) 2e5+5; //200005
	private static Scanner in=new Scanner(System.in);
	private static BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
	private static ArrayList<Integer> v[]=new ArrayList[N];
	private static boolean mark[]=new boolean[N];
	static int choice=Integer.MAX_VALUE,trav=Integer.MAX_VALUE;

	public static void main(String[] args) throws IOException{
		long s=in.nextLong();
		long n=in.nextLong();
		String p;
		double res=pow((double)(n/2.71828),n)/pow((double)(s/2.71828),s);
		if(s!=0&&s!=1)res=(Math.sqrt(n)/Math.sqrt(s))*res;
		else if((s==0||s==1)&&n<5){
			long mult=1;
			for(int i=1;i<=n;i++)
				mult*=i;
			p=""+mult;
			out.println(p.charAt(p.length()-1));
			return;
		}
		else res=0;
		p=""+res;
		out.println(p.charAt(p.length()-1));
	}
}

import java.util.*;

public class Immortality {
	public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double x = 0;

        double a = sc.nextDouble();
        double b = sc.nextDouble();

        double aFact = 1;
        double bFact = 1;

        for(int i=1;i<=a;i++){

            aFact=aFact*i;
        }

        for(int i=1;i<=b;i++){
            bFact=bFact*i;
        }

        x = bFact/aFact;

        System.out.println(x % 10);

    }
}

import java.util.Scanner;

public class EternalMorality {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub

		Scanner input = new Scanner(System.in);
		long a = input.nextLong();
		long b = input.nextLong();
		long total=1;
		for(long i=a+1;i<=b;i++){
			int z =(int) i%10;
			//System.out.println(i);
			if(z==0){
				System.out.println(0);
				return;
			}
			total*=z;
			total = total%10;

		}
		System.out.println(total);
	}

}

import java.util.Scanner;

public class EternalImmortality {

    public static void main(String[] args) {
        EternalImmortality eternalImmortality = new EternalImmortality();
        Scanner scanner = new Scanner(System.in);
        int a = scanner.nextInt();
        int b = scanner.nextInt();
        System.out.println(eternalImmortality.solve(a, b));
    }

    private int solve(int a, int b) {
        int counter = 1;

        for (int i = a+1; i <= b; i++) {
            counter *= lastDigit(i);
            counter = lastDigit(counter);
            if (counter == 0) {
                return 0;
            }
        }

        return counter;
    }

    private int lastDigit(int n) {
        return (n/10) * 10;
    }
}

import java.util.*;
public class Main
{
     static int fact(int n)
    {
        if(n==0)
        return 1;

        return n*fact(n-1);
    }
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long a=sc.nextLong();
		long b=sc.nextLong();
		if(b-a<5)
		System.out.println(fact((int)(b-a))%10);
        else
        System.out.println(0);
	}
}

import java.util.Scanner;

public class a_869B {
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        long a = s.nextLong(), b=s.nextLong();
        long diff = b-a;
        if(diff>1)
        {
            System.out.println(diff%2==1?(diff%10)*2:diff%10);
        }
        else
        {
            System.out.println(b%10);
        }

    }
}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class B {

	public static void main(String[] args)  {
		FastScanner scan = new FastScanner();
		PrintWriter out = new PrintWriter(System.out);
		long a = scan.nextLong(), b = scan.nextLong();
		if(b-a >= 10) out.println(0);
		else {
			long res = 1;
			for(long i = a+1; i <= b; i++) res *= i;
			out.println(res%10);
		}
		out.close();
	}

	static class FastScanner {
		BufferedReader br;
		StringTokenizer st;

		public FastScanner() {
			try	{
				br = new BufferedReader(new InputStreamReader(System.in));
				st = new StringTokenizer(br.readLine());
			} catch (Exception e){e.printStackTrace();}
		}

		public String next() {
			if (st.hasMoreTokens())	return st.nextToken();
			try {st = new StringTokenizer(br.readLine());}
			catch (Exception e) {e.printStackTrace();}
			return st.nextToken();
		}

		public int nextInt() {return Integer.parseInt(next());}

		public long nextLong() {return Long.parseLong(next());}

		public double nextDouble() {return Double.parseDouble(next());}

		public String nextLine() {
			String line = "";
			if(st.hasMoreTokens()) line = st.nextToken();
			else try {return br.readLine();}catch(IOException e){e.printStackTrace();}
			while(st.hasMoreTokens()) line += " "+st.nextToken();
			return line;
		}

		public int[] nextIntArray(int n) {
			int[] a = new int[n];
			for(int i = 0; i < n; i++) a[i] = nextInt();
			return a;
		}

		public long[] nextLongArray(int n){
			long[] a = new long[n];
			for(int i = 0; i < n; i++) a[i] = nextLong();
			return a;
		}

		public double[] nextDoubleArray(int n){
			double[] a = new double[n];
			for(int i = 0; i < n; i++) a[i] = nextDouble();
			return a;
		}

		public char[][] nextGrid(int n, int m){
			char[][] grid = new char[n][m];
			for(int i = 0; i < n; i++) grid[i] = next().toCharArray();
			return grid;
		}
	}

}

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int a = in.nextInt();
        int cnt=0,i;
        int b = in.nextInt();
        if(b==a){System.out.println("1"); System.exit(0);}
        else if(b-a>9)System.out.println("0");
        else
        { while(a>10){a = a%10;}
          while(b>10){b = b%10;}
         if(a>b)System.out.println("0");
            else if(a==1){
                if(b==2)System.out.println("2");
                else if(b==3)System.out.println("6");
                else if(b==4)System.out.println("4");
                else System.out.println("0");

            }

            else if(a==2){
              if(b==3)System.out.println("3");
                else if(b==4)System.out.println("2");
                else System.out.println("0");

            }

          else if(a==3){
              if(b==4)System.out.println("4");
              else System.out.println("0");

            }

          else if(a==4){
              if(b==5)System.out.println("5");
              else System.out.println("0");

            }

          else if(a==5){
              if(b==6)System.out.println("6");
                else if(b==7)System.out.println("2");
                else if(b==8)System.out.println("6");
                else if(b==9)System.out.println("4");
                else System.out.println("0");

            }

          else if(a==6){
              if(b==7)System.out.println("7");
                else if(b==8)System.out.println("6");
                else if(b==9)System.out.println("4");
              else System.out.println("0");

            }

           else if(a==7){
              if(b==8)System.out.println("8");
                else if(b==9)System.out.println("2");
                else System.out.println("0");

            }

         else if(a==8){
              if(b==9)System.out.println("9");
              else System.out.println("0");

            }
         //else System.out.println("0");

        }

       }
}

import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        String[] input = scanner.nextLine().split(" ");

        long a = Integer.parseInt(input[0]);
        long b = Integer.parseInt(input[1]);
        //System.out.println(answer);
        String answer1 = String.valueOf(run(a, b));
        System.out.println(answer1.charAt(answer1.length() - 1));
    }

    private static long run(long a, long b){
        long test1 = 1;
        for (long i = 2; i <= a; i++) {
            test1 = (test1 * (i % 10)) % 10;
        }
        //System.out.println(test1);
        return test1;
    }
}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class ProblemB {

	public static void main(String[] args) throws IOException{
		// TODO Auto-generated method stub
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String input[] = br.readLine().split(" ");
		long a = Long.parseLong(input[0]);
		long b = Long.parseLong(input[1]);
		long res = 1;
		if (a % 10 == 0 || b % 10 == 0) {
			System.out.println(0);
		}else {
		for (long i = a + 1; i <= b; i++) {
			res = (res * (i % 10)) % 10;
		}
		System.out.println(res);
		}
	}

}

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()) {
            long a = sc.nextLong();
            long b = sc.nextLong();
            if(b-a>10 || a>b) {
                System.out.println("0");
            } else {
                Long tmp = 1L;
                a = a %1000;b=b%1000;
                while (a<b){
                    a = a+1;
//                    if(a%10==0) continue;
                    tmp = tmp * (a) % 100;
                }
                System.out.println(tmp%10);
            }
        }
    }
}

import java.util.*;
public class Main
{
     static long fact(int n,long b)
    {
        long k= b-1;
     for(int i=1;i<n;i++)
     {
         b=b*k;
         k--;
     }
       return b;
    }
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long a=sc.nextLong();
		long b=sc.nextLong();
		if(b-a<5)
		System.out.println(fact((int)(b-a),b)%10);
        else
        System.out.println(0);
	}
}

import java.io.*;
import java.util.*;
public class eternal
{
    public static void main(String args[])throws IOException
    {
        Scanner in = new Scanner(System.in);
        long a , b ;
        a=in.nextLong();
        b=in.nextLong();
        long  fb=1 ;
       if(b-a>10)
            System.out.println("0     c");
       else
       {
        for(long i=a+1;i<=b;i++)

           fb=((fb%10)*(i%10))%10;

           System.out.println((int)(fb));
       }

    }
}

import java.util.*;
import java.math.*;
public class TheEternalImmortality {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong(), b = sc.nextLong();
		long r=1;

		if((b%10 == 0)||(a%10<b%10))
		{
			r=0;
		}
		else
		{
			for(long i=a+1; i<=b; i++)
			{
				r = r*(i%10);
			}
		}

		System.out.println(r%10);
	}

}

import java.util.*;
public class Main{
public static void main(String[] args){

Scanner scan=new Scanner(System.in);
long a=scan.nextLong();
long b=scan.nextLong();

if(b<a){System.out.println("0");}

if(b==a){
	System.out.println("1");
}
if(b>a){

	if(b-a>=5){
		System.out.println("0");
	}else{

		long multiply=1;
	for(long i=a+1;i<=b;i++){
		multiply=multiply*i;

	}

	System.out.println(multiply%10);

	}

}

}
}

import java.util.Scanner;

public class Codeforce {

    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        long a=sc.nextLong();
                long b=sc.nextLong();
                long p=1,t=0;
           t=b-a;
         for(int i=0;i<t;i++){
            p=p*b;
            b--;
         }
         System.out.println(p%10);
       }
}

import java.util.*;

public class EternalImmortality{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt(), b = sc.nextInt();
        if(a == b){
            System.out.println(1);
            return;
        }
        int res = 1;
        for( int i = a + 1; i <= b; i++){
            res *= i;
        }
        System.out.println(res%10);
    }
}

import java.util.Scanner;

public class a_869B {
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        long a = s.nextLong(), b=s.nextLong();
        long diff = b-a;
        if(diff>5) // must include a (5 with an even number) or a (10)
        {
            System.out.println(0);
        }
        else if(diff==1)  //  b!/(b-1)! = b
        {
            System.out.println(b%10);

        }
        else if(diff==0)  //  b!/b! = 1
        {
            System.out.println(1);
        }
        else // diff: 2,3,4  // do it manually !
        {
            int res=1;
            for (long x = b; x > a ; x--) {
                res*=x;
                res%=10;
            }
            System.out.println(res%10);
        }

    }
}

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

import java.math.BigInteger;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Scanner;

/**
 *
 * @author ayman
 */
public class Qualifications {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        BigInteger a = new BigInteger(sc.next());
        BigInteger b = new BigInteger(sc.next());
        BigInteger re = BigInteger.ONE;
//        System.out.println(a);
//        System.out.println(b);
        int l = (int)(b.add(a.multiply(BigInteger.valueOf(-1)))).longValue();
//        System.err.println(l);
        if (l <= 3 && l > 0) {
//            System.err.println("dsadsd");
            for (int i = l; i >= 0; i--) {
//                System.err.println("dd");

                re = b.multiply(b.subtract(BigInteger.ONE));
            }

            System.out.println(re.remainder(BigInteger.valueOf(10)));
        }else{
            System.out.println("0");
        }

    }
}

import java.util.*;

public class Immortality {
	public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int x = 0;

        int a = sc.nextInt();
        int b = sc.nextInt();

        int aFact = factorial(a);
        int bFact = factorial(b);

        x = (bFact/aFact) % 10;

        System.out.println(x);

    }

    public static int factorial(int y){
        int fact = 1;
        for(int i=1;i<=y;i++){
            fact=(fact % 10) * (i % 10);
            if(fact % 10 == 0){
                break;
            }
        }
        return fact;

     }

}

import java.util.Arrays;
import java.util.Scanner;

public class Tako {
	public static void main(String[] args){

		Scanner s = new Scanner(System.in);

		long x = s.nextLong();
		long y = s.nextLong();

		if(x==y){
			System.out.println("1");
		}

		if(y-x>=5)
			System.out.println("0");
		else{
			long ans = y%10;
			long z = y-x;
			for (int i = 1; i < z; i++) {
				 ans = (ans * (y-i))%10;
			}
			System.out.println(ans%10);
		}
	}
}

import java.io.*;
import java.util.*;
public class B869
{

    public static void main(String args[])throws IOException
    {
        BufferedReader br= new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out= new PrintWriter(System.out);
        //double a=in.nextDouble();
        //double b=in.nextDouble();
        StringTokenizer str= new StringTokenizer(br.readLine());
        String a1= str.nextToken();
        String b1= str.nextToken();

        if(a1.equals(b1))
        {
            out.println(1);
            out.flush();
            return;
        }
        int i;
        for(i=0; i< b1.length(); i++)
        {
            if(a1.charAt(i)!=b1.charAt(i))
            {
                break;
            }
        }
        double a= Double.parseDouble(a1.substring(i));
        double b= Double.parseDouble(b1.substring(i));
        double prod=1;

        if(a+1==b)
        prod=b%10;
        else
        {
            x:
            for(i=(int)a+1; i<=b; i++)
            {
                prod*= i%10;
                prod= prod%10;
                if(prod==0)
                break x;
            }
        }
        out.println((long)prod);
        out.flush();
    }

}

	/*package whatever //do not write package name here */
import java.io.*;
import java.util.*;
import java.math.*;
public final  class Contest
{
	 static class FastReader
	    {
	        BufferedReader br;
	        StringTokenizer st;

	        public FastReader()
	        {
	            br = new BufferedReader(new
	                     InputStreamReader(System.in));
	        }

	        String next()
	        {
	            while (st == null || !st.hasMoreElements())
	            {
	                try
	                {
	                    st = new StringTokenizer(br.readLine());
	                }
	                catch (IOException  e)
	                {
	                    e.printStackTrace();
	                }
	            }
	            return st.nextToken();
	        }

	        int nextInt()
	        {
	            return Integer.parseInt(next());
	        }

	        long nextLong()
	        {
	            return Long.parseLong(next());
	        }

	        double nextDouble()
	        {
	            return Double.parseDouble(next());
	        }

	        String nextLine()
	        {
	            String str = "";
	            try
	            {
	                str = br.readLine();
	            }
	            catch (IOException e)
	            {
	                e.printStackTrace();
	            }
	            return str;
	        }
	    }

    public static void main(String args[]) throws IOException
    {
    	FastReader sc=new FastReader();
    	long a=sc.nextLong();
    	long b=sc.nextLong();
    	long res=1;int fl=0;
    	if(b==a)
    	{
    		System.out.println(1);System.exit(0);
    	}
    	while(b>a)
    	{
    		if(b%5==0)
    		{
    			System.out.println(0);fl=1;break;
    		}
    		res*=b;
    		b--;
    	}
    	if(fl==0)
    		System.out.println(res%10);

    }

}

import java.util.*;
public class The_Eternal_Immortality
{
	public static void main(String ar[])
	{
		Scanner s1 = new Scanner(System.in);
		long a,b;
		a = s1.nextLong();
		b = s1.nextLong();
		if((a == 0 || b-a == 1) && b!=0)
		{
			if(b>=5)
				System.out.println("0");
			else
				System.out.println(b);
		}
		else if(a == b)
			System.out.println("1");
		else if(b-a>=5)
			System.out.println("0");
		else
		{
			int mul = 1;
			for(long i=a+1;i<=b;i++)
			{
				//System.out.println("i: "+i);
				if(i%5==0)
				{
					System.out.println("0");
					return;
				}
				mul *= (i%10);
			}
			System.out.println(mul%10);
		}
		s1.close();
	}
}

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
//package codeforces;
import java.util.*;
/**
 *
 * @author Ashraf
 */
public class ConB {
    public static void main(String []args){
        int a,b;
        Scanner in=new Scanner(System.in);
        a=in.nextInt();
        b=in.nextInt();
        if(a==b){
           System.out.println(1);
           System.exit(0);
        }
        else if(a==0||a==1){
            if(b<10){
                int u=1;
                for(int i=1;i<=b;i++){
                    u=u*i;
                }
                System.out.println(u%10);
                System.exit(0);
            }
            else{
                System.out.println(0);
                System.exit(0);
            }
        }
        else{
            int x=b-a;
            StringBuilder sb=new StringBuilder();
            sb.append("");
            sb.append(b);
            String s=sb.toString();
            char c=s.charAt(s.length()-1);
            int p=Character.getNumericValue(c);
            if(p==0){
                System.out.println(0);
                System.exit(0);
            }
            else{
                int u=1;
                for(int i=0;i<x;i++){
                    u=u*p;
                    p--;
                    if(p==0){
                        System.out.println(0);
                        System.exit(0);
                    }
                }
                System.out.println(u%10);
                System.exit(0);
            }
        }
    }
}

import java.util.*;
import java.io.*;
/**
 *
 * @author alanl
 */
public class Main{
    static BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
    static StringTokenizer st;
    static PrintWriter pr = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
    public static void main(String[] args) throws IOException{
        long a = readLong(), b = readLong(), diff = b-a, sub = b, sub1 = diff;
        boolean zero = false;
        int cur = 0;
        while(cur<10 && sub1>0){
            sub--;
            sub1--;
            if(sub1==0)break;
            cur++;
            if(sub<1)break;
            if(sub%5==0){
                zero = true;
                break;
            }
        }
        if(zero){
            println(0);
            return;
        }
        else{
            String[]val = Long.toString(b).split("");
            int cnt = Integer.parseInt(val[val.length-1]);
            long ans = 1;
            while(cnt>1&&diff>0){
                ans*=cnt;
                cnt--;
                diff--;
            }
            if(ans==1){
                println(0);
                return;
            }
            val = Long.toString(ans).split("");
            println(val[val.length-1]);
        }
    }
    static String next () throws IOException {
        while (st == null || !st.hasMoreTokens())
                st = new StringTokenizer(input.readLine().trim());
        return st.nextToken();
    }
    static long readLong () throws IOException {
        return Long.parseLong(next());
    }
    static int readInt () throws IOException {
        return Integer.parseInt(next());
    }
    static double readDouble () throws IOException {
        return Double.parseDouble(next());
    }
    static char readChar () throws IOException {
        return next().charAt(0);
    }
    static String readLine () throws IOException {
        return input.readLine().trim();
    }
    static void print(Object b) {
        System.out.print(b);
    }
    static void println(Object b) {
        System.out.println(b);
    }
    static void println() {
        System.out.println();
    }
}

import java.util.Scanner;

public class EternalMorality {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub

		Scanner input = new Scanner(System.in);
		long a = input.nextLong();
		long b = input.nextLong();
		long total=1;
		for(long i=a+1;i<=b;i++){
			int z =(int) i%10;
			//System.out.println(i);
			if(z==0){
				System.out.println(0);
				return;
			}
			total*=z;
			total = total%10;

		}
		System.out.println(total);
	}

}

import java.math.BigInteger;
import java.util.*;
import java.util.stream.IntStream;
import java.util.stream.Stream;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        long a = in.nextLong();
        long b = in.nextLong();

        if (a == b) {
            System.out.println(1);
            return;
        }

        if (b - a == 1) {
            System.out.println(b % 10);
            return;
        }

        long start = a + 1;
        if (start % 10 == 1 && b % 10 == 2 || start % 10 == 3 && b % 10 == 4 || start % 10 == 6 && b % 10 == 7
                || start % 10 == 8 && b % 10 == 9) {
            System.out.println(2);
        } else if ((start % 10 == 1 || start % 10 == 2) && b % 10 == 3
                || start % 10 == 6 && b % 10 == 8) {
            System.out.println(6);
        } else if ((start % 10 == 1 || start % 10 == 2) && b % 10 == 4 ||
                start % 10 == 6 && b % 10 == 9) {
            System.out.println(4);
        }  else {
            System.out.println(0);
        }
    }
}

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()) {
            long a = sc.nextLong();
            long b = sc.nextLong();
            if(b-a>10 || a>b) {
                System.out.println("0");
            } else {
                Long tmp = 1L;
                a = a %1000;b=b%1000;
                if(b==0) b=1000;
                while (a<b){

                    a = a+1;
//                    if(a%10==0) continue;
                    tmp = tmp * (a) % 100;
                }
                System.out.println(tmp%10);
            }
        }
    }
}

import java.util.*;

public class Phoenix {
    public static void main (String [] args) {
	Scanner in = new Scanner (System.in);
	long a=in.nextLong();
	long b=in.nextLong();
	long sum=1;
	while(b>a) {
	    sum*=b;
	    b--;
	}
	long last=sum%10;

	System.out.println (last);
    }
}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.*;

public class Hello {
    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            return str;
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        long nextLong() {

            return Long.parseLong(next());
        }

        BigInteger nextBigIntger() {
            BigInteger bb = new BigInteger(next());
            return bb;
        }
    }
 static long MOD = 1000000007;
    public static void main(String[] args) {
        FastReader sc = new FastReader();
        int a = sc.nextInt();
        int b = sc.nextInt();
        if(b==a)
            System.out.println(1);
        else {
            long ans=b,diff=b-a;
            while(diff>1){
                ans =(ans*(b-1))%(MOD);
                b--;
                diff--;
            }
            System.out.println(ans%10);
        }

    }
}

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

import java.math.BigInteger;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Scanner;

/**
 *
 * @author ayman
 */
public class Qualifications {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        BigInteger a = new BigInteger(sc.next());
        BigInteger b = new BigInteger(sc.next());
        BigInteger re = BigInteger.ONE;
//        System.out.println(a);
//        System.out.println(b);
        int l = (int)(b.add(a.multiply(BigInteger.valueOf(-1)))).longValue();
//        System.err.println(l);
        if (l <= 10 && l > 0) {
//            System.err.println("dsadsd");
            for (int i = l; i >= 0; i--) {
//                System.err.println("dd");

                re = b.multiply(b.subtract(BigInteger.ONE));
            }

            System.out.println(re.remainder(BigInteger.valueOf(10)));
        }else{
            System.out.println("0");
        }

    }
}

import java.util.*;
import java.math.BigInteger;
public class TheEternalImmortality {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		long a,b,i,k;

		a = sc.nextLong();
		b = sc.nextLong();

		i = b -a;
		k =b;

		for(long j = i; j>1;j--)
		{
			k--;
			a = b*(k);
		}

		System.out.println(a%10);

	}

}

import java.math.BigInteger;
import java.util.Scanner;

public class B {
	public static void main(String[]args){
		Scanner sc = new Scanner(System.in);
		BigInteger bg = sc.nextBigInteger();
		BigInteger bg2 = sc.nextBigInteger();
		BigInteger bg3 = BigInteger.ONE;

	while(!(bg.equals(bg2))){
			bg=bg.add(BigInteger.ONE);
			System.out.println(bg.toString());
			bg3=bg3.multiply(bg);
			if(bg3.mod(BigInteger.TEN).equals(0)){
				break;
			}
		}
		System.out.println(bg3.mod(BigInteger.TEN));
	}
}

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args) throws Throwable
	{
		Scanner sc = new Scanner((System.in));
		long a = sc.nextLong() , b = sc.nextLong();
		long last = b-- % 100;
		BigInteger ten = new BigInteger(10+"");
		while(b > a && last != 0)
		{
			BigInteger tmp = new BigInteger(b+"");
			tmp = tmp.multiply(new BigInteger(last+""));
			last = Integer.parseInt(tmp.mod(ten).toString());
			last %= 10;
			b--;
		}

		System.out.println(last % 10);
	}

	static class Scanner
	{
		StringTokenizer st;
		BufferedReader br;
		public Scanner(InputStream s){	br = new BufferedReader(new InputStreamReader(s));}
		public Scanner(String s) throws FileNotFoundException {
			br = new BufferedReader(new FileReader(s));
		}
		public String next() throws IOException
		{
			while (st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine());
			return st.nextToken();
		}
		public int nextInt() throws IOException {return Integer.parseInt(next());}
		public String nextLine() throws IOException {return br.readLine();}
		public long nextLong() throws IOException {return Long.parseLong(next());}
		public double nextDouble() throws IOException {return Double.parseDouble(next());}
		public boolean ready() throws IOException {return br.ready();}
	}
}

import java.util.*;
import java.util.ArrayList;
public class Main{

   static class Pair
   {
      int x;
      int y;

      Pair(int x, int y){
         this.x=x;
         this.y=y;
      }

   }

    public static void main(String[] args){

        Scanner param=new Scanner(System.in);
          long n=param.nextLong();
          long s=param.nextLong();
           long sum=1;
           if(n==0){
              System.out.println(s%10);
              return ;
           }
           while(s!=n){
              sum*=s;
              s--;
           }
           System.out.println(sum%10);

}
}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class A{
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());
		long a = Long.parseLong(st.nextToken());
		long b = Long.parseLong(st.nextToken());
		if(a == b)
		{
			System.out.println(1);
			return;
		}
		if(b - a > 4)
		{
			System.out.println(0);
			return;
		}
		if(b - a == 4)
		{
			System.out.println(4);
			return;
		}
		if(b - a == 3)
		{
			System.out.println(6);
			return;
		}
		if(b - a == 2)
		{
			System.out.println(2);
			return;
		}
		if(b - a == 1)
		{
			System.out.println(b % 10);
			return;
		}
	}

}

import java.io.PrintWriter;
import java.util.Scanner;

public class phoenix {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out, true);

		long a = (in.nextLong() + 1);
		long b = in.nextLong();

		if (b - a > 10)
		{
			out.println(0);
			System.exit(0);
		}

		long fact = 1;
		int k=1;
		a %= 100;
		b %= 100;

		for (; a <= b ; a++)
		{
			fact *= a;
			k ++;
			if (k > 10)
			{
				out.println(0);
				System.exit(0);
			}
		}

		out.println(fact % 10);

		in.close();
	}

}

import java.util.Scanner;

public class Codeforce {

    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        long a=sc.nextLong();
                long b=sc.nextLong();
                long p=1,t=0;
           t=b-a;
         for(int i=0;i<t;i++){
            p=p*b;
            b--;
         }
         System.out.println(p%10);
       }
}

import java.util.Scanner;

public class phoenix {
	public static void main(String[] args) {
		long n, m;
		Scanner var1 = new Scanner(System.in);
		n = var1.nextLong();
		m = var1.nextLong();
		System.out.println(factorial(n,m));
	}
	public static long factorial (long var1, long var2) {
		long result = 1;
		long cnt = var2 - var1;
		if (cnt>=10) return 0;
		for (long i=(var1+1); i<=var2; i++) result = (i%10);
		return result%10;
		}
	}

/*
######  ######    #####  ######  ######  #####
 #   #  #    #      #    #    #  #    #    #
 #   #  # #  #      #    # ## #  # ## #    #
 #   #  #  #    #   #    #    #  #    #    #
######  #   #   # # #    #    #  #    #    #
 */
import java.util.*;
import java.io.*;
public class factorial {
    public static void main(String args[] ) throws Exception {
        Scanner scan = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        int t = scan.nextInt();
        int t1 = scan.nextInt();
        int res = t1-t;
        int fact =1;
        if(res>=5){
            System.out.println("0");
        }else{
            for (int c =t+1 ; c <= t1 ; c++ ){
                fact = fact*c;
               // System.out.println(t+" "+t1+" "+c);
            }
            String s = ""+fact;
            System.out.println(s.charAt(s.length()-1));
        }

    }

}

import java.util.*;
public class TheEternalImmortality {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		long a,b,i,k;

		a = sc.nextLong();
		b = sc.nextLong();

		i = b-a;
		k =b;

		for(long j =1; j<i;j++)
		{
			k--;
			a = b*(k);

		}

		System.out.println(a%10);

	}

}

import java.util.Scanner;

public class phoenix {
	public static void main(String[] args) {
		long n, m;
		Scanner var1 = new Scanner(System.in);
		n = var1.nextLong();
		m = var1.nextLong();
		System.out.println(factorial(n,m));
	}
	public static long factorial (long var1, long var2) {
		long result = 1;
		long cnt = var2 - var1;
		if (cnt>=10) return 0;
		for (long i=(var1+1); i<=var2; i++) result *= i;
		return result%10;
		}
	}

import java.util.*;

public class The_Eternal_Immortality{
  public static final int MODULO = 10;
  public static void main(String[] args){
    Scanner in = new Scanner(System.in);
    long a = in.nextLong();
    long b = in.nextLong();
    if( a == 0 ){
      a = 1;
    }
    if( b == 0 ){
      b = 1;
    }
    if( b - a >= MODULO ){
      System.out.println(0);
    }
    else{
      long res = (a+1) % MODULO;
      for( long i = a + 2; i <= b; i++ ){
        long lastDigit = i % MODULO;
        res *= lastDigit;
      }
      System.out.println(res%MODULO);
    }
  }
}

import java.util.*;
public class Main {
  public static void main(String[] args) {
    Scanner input = new Scanner(System.in);
    long n = input.nextLong();
    long m = input.nextLong();
    long mult = 1;
    for(long i=m;i>n;i--)
      mult = mult*i;
    long g = mult%10;
    System.out.println(g);
  }
}

	/*package whatever //do not write package name here */
import java.io.*;
import java.util.*;
import java.math.*;
public final  class Contest
{
	 static class FastReader
	    {
	        BufferedReader br;
	        StringTokenizer st;

	        public FastReader()
	        {
	            br = new BufferedReader(new
	                     InputStreamReader(System.in));
	        }

	        String next()
	        {
	            while (st == null || !st.hasMoreElements())
	            {
	                try
	                {
	                    st = new StringTokenizer(br.readLine());
	                }
	                catch (IOException  e)
	                {
	                    e.printStackTrace();
	                }
	            }
	            return st.nextToken();
	        }

	        int nextInt()
	        {
	            return Integer.parseInt(next());
	        }

	        long nextLong()
	        {
	            return Long.parseLong(next());
	        }

	        double nextDouble()
	        {
	            return Double.parseDouble(next());
	        }

	        String nextLine()
	        {
	            String str = "";
	            try
	            {
	                str = br.readLine();
	            }
	            catch (IOException e)
	            {
	                e.printStackTrace();
	            }
	            return str;
	        }
	    }

    public static void main(String args[]) throws IOException
    {
    	FastReader sc=new FastReader();
    	long a=sc.nextLong();
    	long b=sc.nextLong();
    	long res=1;int fl=0;
    	while(b>a)
    	{
    		if(b%5==0)
    		{
    			System.out.println(0);fl=1;break;
    		}
    		res*=b;
    		b--;
    	}
    	if(fl==0)
    		System.out.println(res%10);

    }

}

import java.util.*;
import java.io.*;

public class Main {
  public static void main (String[] args) {
    Scanner sc = new Scanner(System.in);
    //BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    OutputStream out = new BufferedOutputStream ( System.out );
    String n = sc.next();
    String m = sc.next();
    int a = n.charAt(n.length()-1);
    int b = m.charAt(m.length()-1);
    int ans = -1;
    if(a >= b) {
      ans = 0;
    }
    else {
      int temp = 1;
      for(int i = b; i > a; i--) {
        temp *= i;
      }
      ans = temp % 10;
    }
    System.out.println(ans);
  }
}

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class EternalImmortality{

	public static void main(String[] args){
		Scanner scanner = new Scanner(System.in);

		long firstValue = scanner.nextLong();
		long secondValue = scanner.nextLong();
		long temp;

		// firstValue always greater than secondValue
		if(secondValue > firstValue){
			temp = secondValue;
			secondValue = firstValue;
			firstValue = temp;
		}

		Boolean isZero = false;
		long lastValue = 0;
		long totalFirst = 1;

		for(long i=secondValue+1; i<=firstValue; i++){
			String value = String.valueOf(totalFirst);
			totalFirst = Integer.parseInt(value.substring(value.length()-1));

			totalFirst = totalFirst*i;

			value = String.valueOf(totalFirst);
			totalFirst = Integer.parseInt(value.substring(value.length()-1));

			lastValue = totalFirst;
			if(value.substring(value.length()-1).equals("0")){
				isZero = true;
				lastValue = 0;
				break;
			}
		}

		System.out.println(lastValue);
	}

}

import java.io.*;
import java.util.*;
public class B869
{
    public static void main(String args[])throws IOException
    {
        BufferedReader br= new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out= new PrintWriter(System.out);

        StringTokenizer str= new StringTokenizer(br.readLine());

        long a= Long.parseLong(str.nextToken());
        long b= Long.parseLong(str.nextToken());
        long temp=0;
        if(a>b)
        {
            temp= b;
            b= a;
            a= temp;
        }
        long prod=1;
        int i;
        for(i=(int)a+1; i<=b; i++)
        {
            prod=prod*i;
        }
        out.println(prod%10);
        out.flush();
    }
}

import java.io.*;
import java.util.*;
import java.math.*;
public class GFG {
	public static void main (String[] args) {
		Scanner sc=new Scanner(System.in);
		BigInteger a=sc.nextBigInteger();
		BigInteger b=sc.nextBigInteger();
		BigInteger c=b.subtract(a);
		BigInteger ten=new BigInteger("10");
		BigInteger five=new BigInteger("5");
		int x=c.compareTo(five);
		if(x==1)
		System.out.println("0");
		else if(x==0){
		    System.out.println("1");
		}else{
		    int m1=(a.mod(ten)).intValue();
		    int m2=(b.mod(ten)).intValue();
		    int d=m2-m1;
		    if(d<0)
		    System.out.println("0");
		    else
		    {
		        int ans=1;
		        for(int i=m1+1;i<=m2;i++)
		        ans*=i;
		        System.out.println(ans%10);
		    }
		}
	}
}

import java.util.*;
public class Main
{
     static long fact(long n,long b)
    {
        long k= b-1 % 10;
        b=b % 10;
     for(int i=1;i<n;i++)
     {
         b=b*k;
         k--;
     }
       return b;
    }
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long a=sc.nextLong();
		long b=sc.nextLong();
		if(b-a<5)
		System.out.println(fact((b-a),b)%10);
        else
        System.out.println(0);
	}
}

import java.util.Scanner;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args) {

		long  a,b;

		Scanner sc = new Scanner(System.in);
		while(sc.hasNextLine()) {

			StringTokenizer line = new StringTokenizer(sc.nextLine());
			a = Long.parseLong(line.nextToken());
			b = Long.parseLong(line.nextToken());

			if(a==b) {System.out.println(1);}
			else if(b-a==1){System.out.println(b);}
			else {
				long counter = b-a-1;
				long helper, result=b;

				for(;counter>0;counter--) {

				helper = b - 1;
				result = result * helper;
				b--;

				}

				String s = Long.toString(result);

				System.out.println(s.charAt(s.length()-1));

			}

		}

	}

}

import java.util.Scanner;

public class sss {
	 static Scanner read=new Scanner(System.in);

	public static void main(String[] args) {

String a=read.next();
String  b=read.next();
int A;
int B;
if (a.length()>=10){
 A=Integer.parseInt(a.substring(a.length()-9 , a.length()));
}
else {A=Integer.parseInt(a);
}
if (b.length()>=10){
	 B=Integer.parseInt(b.substring(b.length()-9 , b.length()));
	}
	else {B=Integer.parseInt(b);
	}
int s=1;
if (A+1==0 || B==0) s=0;
else{
if (B-A-1 > 10) s=0;
else{
for(int i=A+1;i<=B;i++){
	s=s*(i%10);
if (s>=10) s=s%10;

}
}
}

System.out.println(s);
	}}

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
//package codeforces;
import java.util.*;
/**
 *
 * @author Ashraf
 */
public class ConB {
    public static void main(String []args){
        int a,b;
        Scanner in=new Scanner(System.in);
        a=in.nextInt();
        b=in.nextInt();
        if(a==b){
           System.out.println(1);
           System.exit(0);
        }
        else if(a==0||a==1){
            if(b<10){
                int u=1;
                for(int i=1;i<=a;i++){
                    u=u*i;
                }
                System.out.println(u%10);
                System.exit(0);
            }
            else{
                System.out.println(0);
                System.exit(0);
            }
        }
        else{
            int x=b-a;
            StringBuilder sb=new StringBuilder();
            sb.append("");
            sb.append(b);
            String s=sb.toString();
            char c=s.charAt(s.length()-1);
            int p=Character.getNumericValue(c);
            if(p==0){
                System.out.println(0);
                System.exit(0);
            }
            else{
                int u=1;
                x=b-a;
                for(int i=0;i<x;i++){
                    u=u*p;
                    p--;
                    if(p==0){
                        System.out.println(0);
                        System.exit(0);
                    }
                }
                System.out.println(u%10);
                System.exit(0);
            }
        }
    }
}

import java.util.*;

public class Phoenix {
    public static void main (String [] args) {
	Scanner in = new Scanner (System.in);
	int a=in.nextInt();
	int b=in.nextInt();
	long sum=1;
	while(b>a) {
	    sum*=b;
	    b--;
	}
	long last=sum%10;

	System.out.println (last);
    }
}

import java.util.Scanner;

public class a_869B {
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        long a = s.nextLong(), b = s.nextLong();
        long res=1;
        for (long x = b; x > a ; x--) {
            res*=x;
        }
        System.out.println(res%10);
    }
}

import java.util.*;
public class Q869B
{
	public static void main(String dfg[])
	{
		Scanner sc=new Scanner(System.in);
		int a=sc.nextInt();
		int b=sc.nextInt();
		int c=b-a;
		if(a==b)
		{
		System.out.println("1");

		}

		else if(c==1)
		{
		System.out.println(b%10);

		}
		else
		{
		int f=1;
		for(int x=1;x<=c;x++)
		{
			f=f*b--;

		}
		System.out.println(f);
		}
	}
}

import java.util.*;
/**
 * Created by CUONG on 10/8/2017.
 */
public class PS869B {
    public static void main(String[] args)
    {
        Scanner s= new Scanner(System.in);
        long a= s.nextLong();
        long b= s.nextLong();
        int c= (int)(b%10); int d= (int)(a%10);
        int diff= (int)(b-a); int ans=0;
        if (diff<5)
        {
            int temp=1;
            for (int i=c; i>c-diff; i--)
            {
                temp*=i;
            }
            ans= temp%10;
        }

        System.out.println(ans);
    }
}

import java.util.Scanner;

public class EternalImmortality {

    public static void main(String[] args) {
        EternalImmortality eternalImmortality = new EternalImmortality();
        Scanner scanner = new Scanner(System.in);
        int a = scanner.nextInt();
        int b = scanner.nextInt();
        System.out.println(eternalImmortality.solve(a, b));
    }

    private int solve(int a, int b) {
        int counter = 1;

        for (int i = a+1; i <= b; i++) {
            counter *= lastDigit(i);
            counter = lastDigit(counter);
            if (counter == 0) {
                return 0;
            }
        }

        return counter;
    }

    private int lastDigit(int n) {
        return (n/10) * 10;
    }
}

import java.io.*;
import java.util.*;

public class b{

	public static void main(String []ar){

		long a,b;
		Scanner cs = new Scanner(System.in);
		a = cs.nextLong();
		b = cs.nextLong();

		long result = 0;

		if (b>a && a>0) {
		    result = 1;
		    long i = a+1;
		    while (i<=b) {
		        result *=i;
		        i++;
		    }
		}

		System.out.println(result%10);

	}

}

import java.util.*;

public class Main2 {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int a = in.nextInt();
        int b = in.nextInt();

        int f = 1;
        for (int e = a + 1; e <= b; e++) {
            f = f * e;
        }

        System.out.print(f % 10);
    }
}

import java.util.*;

public class EternalImmortality{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt(), b = sc.nextInt();
        if(a == b){
            System.out.println(1);
            return;
        }
        int res = 1;
        for( int i = a + 1; i <= b; i++){
            res *= i;
        }
        System.out.println(res%10);
    }
}

import java.util.Scanner;

public class Solutions{

     public static void main(String []args){
        Scanner input = new Scanner(System.in);
        long a = input.nextInt();
        long b = input.nextInt();

        System.out.println((b*(b-1))%10);
}
}

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class CF869B {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		SolutionCF869B sl = new SolutionCF869B();
		BigInteger a = sc.nextBigInteger();
		BigInteger b = sc.nextBigInteger();
		sl.solve(a, b);

	}
}

class SolutionCF869B {
	public void solve(BigInteger a, BigInteger b) {
		BigInteger c = b.subtract(a);
		if (c.intValue() > 4) {
			System.out.println("0");
		} else {
			BigInteger d = BigInteger.ONE;
			for (int i = 1; i <= c.intValue(); i++) {
				d = d.multiply(a.add(new BigInteger(i + "")));
			}
			String out = d.toString();
			System.out.println(out.charAt(out.length() - 1));
		}
	}
}

import java.util.Scanner;

public class dragonyears {
	static long a, b;
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		a = sc.nextLong(); b = sc.nextLong();

		long num;

		long dif = b - a;

		dif = dif % 10;
		num = fact(dif);
		System.out.println(num % 10);

	}

	private static long fact(long dif) {
		if(dif == 0) return 0;
		if(dif == 1) return b;
		long fact = 1;
		while(dif > 1) {
			fact *= dif;
			dif--;
		}
		return fact;
	}

}

import java.util.Scanner;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args) {

		long  a,b;

		Scanner sc = new Scanner(System.in);
		while(sc.hasNextLine()) {

			StringTokenizer line = new StringTokenizer(sc.nextLine());
			a = Long.parseLong(line.nextToken());
			b = Long.parseLong(line.nextToken());

			if(a==b) {System.out.println(1);}
			else if(b-a==1){System.out.println(b);}
			else {
				long counter = b-a;
				long helper, result=1;

				for(;counter>0;counter--) {

				helper = b - 1;
				result = result * b * helper;
				b = b - 1;

				}

				String s = Long.toString(result);

				System.out.println(s.charAt(s.length()-1));

			}

		}

	}

}

import java.util.Scanner;

/**
 *
 * @author mustafa
 */
public class B {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        int a = sc.nextInt();
        int b = sc.nextInt();

        if (a == b)
        {
            System.out.println(1);
            return;
        }

        if (Math.abs(a - b) > 5)
        {
            System.out.println(0);
            return;
        }

        if (a == 0)
        {
            int x = B.faktoriyal(b);
            System.out.println(x % 10);
            return;
        }

        int product = 1;

        for (int i = a + 1; i <= b; i++)
            product *= i;

        System.out.println(product % 10);
    }

    public static int faktoriyal(int n)
    {
        int result = 1;

        for (int i = 1; i <=n; i++)
            result = result * i;

        return result;
    }
}

import java.util.*;
import java.io.*;

public class Main {
  public static void main (String[] args) {
    Scanner sc = new Scanner(System.in);
    //BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    OutputStream out = new BufferedOutputStream ( System.out );
    String n = sc.next();
    String m = sc.next();
    int a = Integer.parseInt("" + n.charAt(n.length()-1));
    int b = Integer.parseInt("" + m.charAt(m.length()-1));
    int ans = -1;
    if(a > b) {
      ans = 0;
    }
    else {
      int temp = 1;
      for(int i = b; i > a; i--) {
        temp *= i;
      }
      ans = temp % 10;
    }
    System.out.println(ans);
  }
}

import java.util.Scanner;

public class NewClass2 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong(),b = sc.nextLong();
        if ((b-a)<=4) {
            long i,k=1;
            for (i = 0; i < b-a-1;i++ ) {
                k*=(b%10)*((b-1)%10);
            }
            System.out.println((k%10));
        }
        else{
            System.out.println(0);
        }
    }
}

import java.util.Scanner;

public class Test  {
    public static void main(String[] args) {

        int a;
        int b;
        int result = 1;
        Scanner sc = new Scanner(System.in);
        a = sc.nextInt();
        b = sc.nextInt();
        int count = b-a;

        if (a == 0) {
            a = 1;
        }

        for (int i=0; i<count; i++){
            result *= b;
            b--;
        }

        System.out.println(result%10);

        sc.close();
    }
}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class B {

	public static void main(String[] args)  {
		FastScanner scan = new FastScanner();
		PrintWriter out = new PrintWriter(System.out);
		long a = scan.nextLong(), b = scan.nextLong();
		if(b-a >= 5) out.println(0);
		else if(b == a) out.println(1);
		else {
			boolean hit = false;
			a++;
			for(long i = a; i <= b; i++) if(i%5 == 0) hit = true;
			if(hit) out.println(0);
			else {
				a %= 5;
				b %= 5;
				long res = 1;
				for(long i = a; i <= b; i++) res *= i;
				out.println(res%10);
			}
		}
		out.close();
	}

	static class FastScanner {
		BufferedReader br;
		StringTokenizer st;

		public FastScanner() {
			try	{
				br = new BufferedReader(new InputStreamReader(System.in));
				st = new StringTokenizer(br.readLine());
			} catch (Exception e){e.printStackTrace();}
		}

		public String next() {
			if (st.hasMoreTokens())	return st.nextToken();
			try {st = new StringTokenizer(br.readLine());}
			catch (Exception e) {e.printStackTrace();}
			return st.nextToken();
		}

		public int nextInt() {return Integer.parseInt(next());}

		public long nextLong() {return Long.parseLong(next());}

		public double nextDouble() {return Double.parseDouble(next());}

		public String nextLine() {
			String line = "";
			if(st.hasMoreTokens()) line = st.nextToken();
			else try {return br.readLine();}catch(IOException e){e.printStackTrace();}
			while(st.hasMoreTokens()) line += " "+st.nextToken();
			return line;
		}

		public int[] nextIntArray(int n) {
			int[] a = new int[n];
			for(int i = 0; i < n; i++) a[i] = nextInt();
			return a;
		}

		public long[] nextLongArray(int n){
			long[] a = new long[n];
			for(int i = 0; i < n; i++) a[i] = nextLong();
			return a;
		}

		public double[] nextDoubleArray(int n){
			double[] a = new double[n];
			for(int i = 0; i < n; i++) a[i] = nextDouble();
			return a;
		}

		public char[][] nextGrid(int n, int m){
			char[][] grid = new char[n][m];
			for(int i = 0; i < n; i++) grid[i] = next().toCharArray();
			return grid;
		}
	}

}

import java.util.*;
public class TheEternalImmortality {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		long a,b,i;

		a = sc.nextLong();
		b = sc.nextLong();

		i = b -a;

		for(long j = i; j>1;j--)
		{
			a = b*(b-1);
		}

		System.out.println(a%10);

	}

}

import java.math.BigInteger;
import java.util.*;
import java.util.stream.IntStream;
import java.util.stream.Stream;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int a = in.nextInt();
        int b = in.nextInt();

        System.out.println(0);
    }
}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class A{
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());
		long a = Long.parseLong(st.nextToken());
		long b = Long.parseLong(st.nextToken());

		if(b - a == 0){
			System.out.println(1);
			return;
		}
		if(b - a == 1){
			System.out.println(b % 10);
			return;
		}

		int count = 0;

		while(b > a && b % 5 != 0)
		{
			count++;
			b--;
		}

		int[] pos = {4 ,6, 2, 0};

		if(b % 5 != 0)
			System.out.println(pos[count]);
		else
			System.out.println("0");

	}

}

import java.math.BigInteger;
import java.util.*;
import java.util.stream.IntStream;
import java.util.stream.Stream;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        long a = in.nextLong();
        long b = in.nextLong();

        long start = a + 1;
        if (start % 10 == 1 && b % 10 == 2 || start % 10 == 3 && b % 10 == 4 || start % 10 == 6 && b % 10 == 7
                || start % 10 == 8 && b % 10 == 9) {
            System.out.println(2);
        } else if ((start % 10 == 1 || start % 10 == 2) && b % 10 == 3
                || start % 10 == 6 && b % 10 == 8) {
            System.out.println(6);
        } else if ((start % 10 == 1 || start % 10 == 2) && b % 10 == 4 ||
                start % 10 == 6 && b % 10 == 9) {
            System.out.println(4);
        }  else {
            System.out.println(0);
        }
    }
}

import java.util.Scanner;

public class dragonyears {
	static long a, b;
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		a = sc.nextLong(); b = sc.nextLong();

		long num;

		long dif = b - a;

		dif = dif % 10;
		num = fact(dif);
		System.out.println(num % 10);

	}

	private static long fact(long dif) {
		if(dif == 0) return 0;
		if(dif == 1) return 1;
		long fact = 1;
		while(dif > 1) {
			fact *= dif;
			dif--;
		}
		return fact;
	}

}

import java.io.*;
import java.util.Locale;
import java.util.StringTokenizer;

public class B {

    private void solve() throws IOException {
        int a = nextInt();
        int b = nextInt();
        int ans = 0;
        if (b - a < 5) {
            b = b % 100;
            a = a % 10;
            ans = 1;
            for (int i = a + 1; i <= b; i++) {
                ans = (ans * (i % 10)) % 10;
            }
        }
        System.out.println(ans);
    }

    private void run() {
        try {
            br = new BufferedReader(new InputStreamReader(System.in));

            solve();

        } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }
    }

    private BufferedReader br;
    private StringTokenizer in;

    private String nextToken() throws IOException {
        while (in == null || !in.hasMoreTokens()) {
            in = new StringTokenizer(br.readLine());
        }
        return in.nextToken();
    }

    private int nextInt() throws IOException {
        return Integer.parseInt(nextToken());
    }

    private double nextDouble() throws IOException {
        return Double.parseDouble(nextToken());
    }

    private long nextLong() throws IOException {
        return Long.parseLong(nextToken());
    }

    public static void main(String[] args) throws IOException {
        Locale.setDefault(Locale.US);
        new B().run();
    }

}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class B {

	public static void main(String[] args)  {
		FastScanner scan = new FastScanner();
		PrintWriter out = new PrintWriter(System.out);
		long a = scan.nextLong(), b = scan.nextLong();
		if(b-a >= 5) out.println(0);
		else if(b == a) out.println(1);
		else {
			boolean hit = false;
			a++;
			for(long i = a; i <= b; i++) if(i%5 == 0) hit = true;
			if(hit) out.println(0);
			else {
				a %= 5;
				b %= 5;
				if(a == 1 && b == 2) out.println(2);
				if(a == 1 && b == 3) out.println(6);
				if(a == 1 && b == 4) out.println(4);
				if(a == 2 && b == 3) out.println(6);
				if(a == 2 && b == 4) out.println(4);
				if(a == 3 && b == 4) out.println(2);
			}
		}
		out.close();
	}

	static class FastScanner {
		BufferedReader br;
		StringTokenizer st;

		public FastScanner() {
			try	{
				br = new BufferedReader(new InputStreamReader(System.in));
				st = new StringTokenizer(br.readLine());
			} catch (Exception e){e.printStackTrace();}
		}

		public String next() {
			if (st.hasMoreTokens())	return st.nextToken();
			try {st = new StringTokenizer(br.readLine());}
			catch (Exception e) {e.printStackTrace();}
			return st.nextToken();
		}

		public int nextInt() {return Integer.parseInt(next());}

		public long nextLong() {return Long.parseLong(next());}

		public double nextDouble() {return Double.parseDouble(next());}

		public String nextLine() {
			String line = "";
			if(st.hasMoreTokens()) line = st.nextToken();
			else try {return br.readLine();}catch(IOException e){e.printStackTrace();}
			while(st.hasMoreTokens()) line += " "+st.nextToken();
			return line;
		}

		public int[] nextIntArray(int n) {
			int[] a = new int[n];
			for(int i = 0; i < n; i++) a[i] = nextInt();
			return a;
		}

		public long[] nextLongArray(int n){
			long[] a = new long[n];
			for(int i = 0; i < n; i++) a[i] = nextLong();
			return a;
		}

		public double[] nextDoubleArray(int n){
			double[] a = new double[n];
			for(int i = 0; i < n; i++) a[i] = nextDouble();
			return a;
		}

		public char[][] nextGrid(int n, int m){
			char[][] grid = new char[n][m];
			for(int i = 0; i < n; i++) grid[i] = next().toCharArray();
			return grid;
		}
	}

}

import java.util.*;
/**
 * Created by CUONG on 10/8/2017.
 */
public class PS869B {
    public static void main(String[] args)
    {
        Scanner s= new Scanner(System.in);
        int a= s.nextInt();
        int b= s.nextInt();
        b=b%10; a=a%10;
        int diff= b-a; int ans=0;
        if (diff<5)
        {
            int temp=1;
            for (int i=b; i>b-diff; i--)
            {
                temp*=i;
            }
            ans= temp%10;
        }

        System.out.println(ans);
    }
}

import java.util.*;
public class The_Eternal_Immortality
{
	public static void main(String ar[])
	{
		Scanner s1 = new Scanner(System.in);
		long a,b;
		a = s1.nextLong();
		b = s1.nextLong();
		if(a == 0 || b-a == 1)
			System.out.println(b%10);
		else if(a == b)
			System.out.println("1");
		else if(b-a>=5)
			System.out.println("0");
		else
		{
			int mul = 1;
			for(long i=a+1;i<=b;i++)
			{
				if(i%5==0)
				{
					System.out.println("0");
					return;
				}
				mul *= (i%10);
			}
			System.out.println(mul%10);
		}
		s1.close();
	}
}

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class CF869B {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		SolutionCF869B sl = new SolutionCF869B();
		BigInteger a = sc.nextBigInteger();
		BigInteger b = sc.nextBigInteger();
		sl.solve(a, b);

	}
}

class SolutionCF869B {
	public void solve(BigInteger a, BigInteger b) {
		BigInteger c = b.subtract(a);
		if (c.intValue() >= 4) {
			System.out.println("0");
		} else {
			BigInteger d = BigInteger.ONE;
			for (int i = 1; i <= c.intValue(); i++) {
				d = d.multiply(a.add(new BigInteger(i + "")));
			}
			String out = d.toString();
			System.out.println(out.charAt(out.length() - 1));
		}
	}
}

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

import java.math.BigInteger;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Scanner;

/**
 *
 * @author ayman
 */
public class Qualifications {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        BigInteger a = new BigInteger(sc.next());
        BigInteger b = new BigInteger(sc.next());
        BigInteger re = BigInteger.ONE;
//        System.out.println(a);
//        System.out.println(b);
        int l = (int) (b.add(a.multiply(BigInteger.valueOf(-1)))).longValue();
//        System.err.println(l);
        if (l == 0) {
            System.out.println(1);
        } else {
            if (l <= 10 && l > 0) {
//            System.err.println("dsadsd");
                for (int i = l; i >= 0; i--) {
//                System.err.println("dd");

                    re = b.multiply(b.subtract(BigInteger.ONE));
                }

                System.out.println(re.remainder(BigInteger.valueOf(10)));
            } else {
                System.out.println("0");
            }
        }
//                BigInteger fac = BigInteger.ONE;
//
//        for(int i =12; i <= 36; i++){
////            for(int j =i; j < 40; j++){
//                fac = fac.multiply(BigInteger.valueOf(i));
//                System.err.println(fac);
////                for(int k = i; k <= j; k++){
////                    fac *= k;
////                }
////                System.err.println(""+ i + " " + j + " " + fac);
//
////            }
//        }
//

    }
}

import java.util.Scanner;

public class Test  {
    public static void main(String[] args) {

        int a;
        int b;
        int result = 1;
        Scanner sc = new Scanner(System.in);
        a = sc.nextInt();
        b = sc.nextInt();
        int count = b-a;

        if (a == 0) {
            a = 1;
        } else {
            for (int i=0; i<count; i++){
                result *= b;
                b--;
            }
        }

        System.out.println(result%10);

        sc.close();
    }
}

import java.math.BigInteger;
import java.util.*;

public class TheEternalImmortality {

	public static void main(String[] args) {

		BigInteger A,B,C;
		C= new BigInteger("1000000000000000000");

		Scanner src = new Scanner (System.in);

		do
		{
			B = src.nextBigInteger();
		}
		while((B.compareTo(BigInteger.ZERO)==-1)||(B.compareTo(C)==1));

		do
		{
			A = src.nextBigInteger();
		}
		while((A.compareTo(BigInteger.ZERO)==-1)||(A.compareTo(C)==1));

		src.close();

		BigInteger r = fact(B).divide(fact(A));

		if(r.compareTo(BigInteger.TEN)== -1)
		{
			System.out.println(r);
		}
		else
		{
			System.out.println(r.mod(BigInteger.TEN));
		}

	}

	public static BigInteger fact(BigInteger n)
	{
		BigInteger k = BigInteger.ONE;

		while(n.equals(BigInteger.ZERO)== false)
		{
			k = k.multiply(n);
			n = n.subtract(BigInteger.ONE);
		}
		return(k);
	}

}