using System;

namespace prog1
{
    class Program
    {
        public static void Main(string[] args)
        {   int n,s;
            s=0;
            n=Convert.ToInt16(Console.ReadLine());
            for (int i=0; i<n; i++) {
                s+=n-i+i*(n-i-1);

            }
            Console.WriteLine(s);

        }
    }
}

using System;

// Codeforces problem 268B "Кнопки"
// http://codeforces.com/problemset/problem/268/B
namespace _268_B
{
	class Program
	{
		static void Main(string[] args)
		{
			#region Read data
			int n = Convert.ToInt32(Console.ReadLine());
			#endregion
			#region Process data
			long result = n;
			for (int i = 1; i <= n; i++)
			{
				result += (n - i) * i;
			}
			#endregion
			#region Write results
			Console.WriteLine(result);
			Console.ReadLine();
			#endregion
		}
	}
}

using System;

namespace CodeForces
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int sum = 0;
            int buttonsFound = 0;
            for (int currentButton = n; currentButton > 0; currentButton--)
            {
                int numberOfAttemptsToFind = currentButton - 1;
                if (currentButton == 1)
                {
                    sum += n;
                }
                else
                {
                    sum += numberOfAttemptsToFind + (buttonsFound * numberOfAttemptsToFind);
                }
                buttonsFound++;
            }
            Console.WriteLine(sum);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace rg
{
    class Program
    {
        static void Main(string[] args)
        {
            int n,i,k=0;

            n = int.Parse(Console.ReadLine());

            for(i=1;i<=n-1;i++)
            {
                k += ((n - i) * i) + 1;

            }

            Console.WriteLine(k+1);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CSharpPrograms.Codeforces
{
    class _268B
    {
        static void Main()
        {
            long n = Convert.ToInt64(Console.ReadLine());
            long total = 0;
            for (int i = 1; i <= n; i++)
            {
                total += (n - (i - 1)) * (i - 1);
            }
            Console.WriteLine(total + n);
        }
    }
}

using System;

class B268 {
    public static void Main() {
        var n = long.Parse(Console.ReadLine());
        Console.WriteLine(n * (n * n + 5) / 6);
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace cf_164_2
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            int s = n;
            for (int i = 1; i <= n-1; i++)
            {
                s += i*(n - i);
            }
            Console.WriteLine(s);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Codeforces
{
    class _268B
    {
        public static void Main()
        {
            int n = int.Parse(Console.ReadLine());
            int s = n;
            for (int i = 1; i < n; i++)
            {
                s = s + i * (n - i);
            }
            Console.WriteLine(s);
        }
    }
}

using System;

namespace MainProgram
{

    class Program
    {
        static void Main(string[] args)
        {
           var n = int.Parse(Console.ReadLine());
           var result = 0;
            for(int i = 1; i < n; i++)
            {
                result += (n-i)*i;
            }
            result += n;
            Console.WriteLine (result);
        }
    }
}

using System;

namespace codeforces
{
    class Program
    {

        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int count = n, ch = n;
            if (n == 1)
                count = 1;
            else if (n == 2)
                count = 3;
            else
            {
                if (n % 2 != 0)
                {

                    int max = ((n - 1) / 2);
                    for (int i = 1; i < max; i++)
                        count += ch = ch + 2 * (max - i);
                    count *= 2;
                    count += 1;
                }
                else
                {

                    int max = (n / 2 - 1);
                    for (int i = 1; i < max; i++)
                        count += ch = ch + 2 * (max - i) + 1;
                    count *= 2;
                    count += ch + 1 + 1;

                }
            }

            Console.WriteLine(count);

        }
    }
}

using System;

class Program {
  static void Main() {
    var n = int.Parse(Console.ReadLine());
    var sum = n;
    for (var i = 1 ; i < n ; i++) sum += (n-i)*i;
    Console.WriteLine(sum);
  }
}

using System;
class Program
    {
        static void Main(string[] args)
        {
            long n = long.Parse(Console.ReadLine());
            long result = n;
            result += (((n * n - n) / 2L) * n);
            result -= ((n * n - n) * (2 * n - 1L) / 6L);
            Console.WriteLine(result);
        }
    }

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _268B
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            int sum = 0, S = 0, s = 0;
            for (int i = 1; i < n; i++)
			{
                sum += (n-1)*i;
                S += i * i;
			}
            for (int i = 1; i <= n; i++)
            {
                s += i;
            }
            Console.Write(s + sum - S);
            Console.ReadLine();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

class Program
{

    public static void Main()
    {
        int n = int.Parse(Console.ReadLine());
        long count = 0;

        long know = 0;

        if (n == 1)
        {
            know = 1;
        }

        for (int i = 0; i < n; i++)
        {
            //Console.WriteLine("know " + know);
            count += know;

            if(know<n){
                for (int j = 0; j < n - know - 1; j++)
                {
                    if (j == 0)
                    {
                        //Console.WriteLine("search " + (1));
                        count +=  1;
                    }
                    else
                    {
                        //Console.WriteLine("search " + (know+1));
                        count += know + 1;
                    }
                }
            }

            know++;

            if(know == n-1)
            {
                know++;
            }
        }

        Console.WriteLine(count);
    }

}

using System;

namespace Application
{
    class Program
    {
        static void Main()
        {
            int n = int.Parse(Console.ReadLine());

            int k = 0;

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

            Console.WriteLine(k+n);

        }
    }
}

using System;

namespace New_task_93485
{
    class Program
    {
        static void Main(string[] args)
        {
            int Buttons = int.Parse(Console.ReadLine());
            int sum = 0;
            int tmp = Buttons;
            bool[,] arr = new bool[Buttons, Buttons];

            for(int i = 0; i < Buttons; i++)
            {
                arr[i, (Buttons-1) - i] = true;
            }
            bool check = true;

            for(int i = 0; i < Buttons; i++)
            {
                for(int j = 0; j < Buttons; j++)
                {
                    if (check)
                    {
                        check = false;
                        sum++;
                    }
                    else
                    {
                        sum += 1 * (i + 1);
                    }
                    if (arr[i, j])
                    {
                        check = true;
                        break;
                    }
                }

            }

            Console.WriteLine(sum);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication22
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            Int64 count = n;

            if (n == 1) { Console.WriteLine(1); return; }

            for (int i = 1; i < n; i++)
            {
                count += (i * (n - i));
            }

            Console.WriteLine(count);
        }
        // 1,2,3         1,2(2)   3(3)  3,3(4) 3,1(5) 3,2(6) 3,2,1

        private static IEnumerable<string> Perms(string source)
        {
            if (source.Length == 1) return new List<string>() { source };

            var perm = from l in source
                       from _x in Perms(string.Join("",
source.Where(x => x != l)
))
                       select l + _x; ;
            return perm;
        }
    }
}

using System;
using System.IO;
using System.Collections.Generic;
using System.Linq;

namespace _1000
{
    class Program
    {
        static void Main(string[] args)
        {
            //Console.SetIn(new StreamReader("input.txt"));
            solve_164A();
        }

        public static void solve_164A()
        {
            int n = Convert.ToInt32(Console.ReadLine());

            int i = 2;
            int total = n;
            int len = n;
            while (--len > 1)
            {
                total += i * (len - 1);
                total += 1;
                i++;

            }
            total += n > 1 ? 1 : 0;

            Console.WriteLine(total);
        }

        public static void solve_betaRound9A()
        {
            string[] yw = Console.ReadLine().Split(' ');

            int y = Convert.ToInt32(yw[0]);
            int w = Convert.ToInt32(yw[1]);

            int diff = 6 - Math.Max(y, w) + 1;
            int numerator = diff == 4 ? 2 : diff == 5 ? 5 : 1;
            int nominator = 6 % diff == 0 ? 6 / diff : diff == 4 ? 3 : 6;
            Console.WriteLine("{0}/{1}", numerator, nominator);
        }

        public static void solve_531A()
        {
            long n = Convert.ToInt32(Console.ReadLine());

            Console.WriteLine((n * (n + 1) / 2) % 2 == 0 ? 0 : 1);
        }

        /*
            The issue here is that you cannot easily calculate 2 to the power to 10000000.
            For that you need big arhithmetique techniques. And even this may not help
            because you need to quickly calculate powers of 2 and then you need to divide
            big integer by short integer values.
            But if you look into the problem you can actually observe that m
            can only give differnt reminders if it is less than n. If n is larger than m
            then you always have the reminder m. Furthermore, we can see by the problem
            statement that m can be maximum 8-digit number. So in order to calculate
            different reminders n must be less then 27). Why 27.
            Well, we know that (2^31) - 1 is the upper integer range int c#. And it is a 10
            digit number. Let't decrease 31 by 1 to see when we have an integer with 8 digits.
            Using calculator it's pretty easy.
         */
        public static void solve_hello2018A()
        {
            int n = Convert.ToInt32(Console.ReadLine());
            int m = Convert.ToInt32(Console.ReadLine());
            int answer = 0;
            if (n >= 27)
            {
                answer = m;
            }
            else
            {
                answer = m % Convert.ToInt32(Math.Pow(2, n));
            }

            Console.WriteLine(answer);
        }

        public static void solve_574B()
        {
            string[] nk = Console.ReadLine().Split(' ');
            int n = Convert.ToInt32(nk[0]);
            int k = Convert.ToInt32(nk[1]);

            int i = 1;
            int count = 1;
            while (i != n && i - count == k)
            {
                i++;
                count += count + 1;
            }

            Console.WriteLine(count);
        }

        public static void solve_574A()
        {
            string[] nk = Console.ReadLine().Split(' ');
            int n = Convert.ToInt32(nk[0]);
            int k = Convert.ToInt32(nk[1]);

            int[] cnt = new int[k];
            for (int i = 0; i < n; i++)
            {
                int p = Convert.ToInt32(Console.ReadLine());

                cnt[p - 1]++;
            }

            Array.Sort(cnt, (int a, int b) => b.CompareTo(a));
            int count = 0;
            int g = 0;
            int j = n % 2 > 0 ? n / 2 + 1 : n / 2;
            for (int i = 0; i < k; i++)
            {
                if (g >= j)
                {
                    break;
                }

                while (cnt[i] > 0 && g < j)
                {
                    int deduct = cnt[i] > 1 ? 2 : 1;
                    cnt[i] -= deduct;
                    count += deduct;
                    g += 1;
                }
                //int deduct = cnt[i] % 2 > 0 ? cnt[i] / 2 + 1 : cnt[i] / 2;
                /*if (j <= 0)
                {
                    break;
                }
                if (j == 1 && deduct > 1)
                {
                    count += 2;
                }
                else if (j == 1 && deduct == 1)
                {
                    count += 1;
                }
                else
                {
                    count += cnt[i];
                }

                j -= deduct;*/
            }

            Console.WriteLine(count);
        }

        public static void solve_352B()
        {
            int n = Convert.ToInt32(Console.ReadLine());
            string test = Console.ReadLine();
            int[] cnts = new int[123];

            for (int i = 0; i < n; i++)
            {
                cnts[test[i]]++;
            }

            int unq = 0;
            for (int i = 0; i < cnts.Length ;i++)
            {
                if (cnts[i] > 0)
                {
                    unq++;
                }
            }

            int answer = -1;

            //Redundancy in condition. if n must be <= 26 then of course unq will be <= 26. So we can remove it.
            if (unq <= 26 && n <= 26)
            {
                answer = n - unq;
            }

            Console.WriteLine(answer);
        }

        public static void solve_2A()
        {
            int n = Convert.ToInt32(Console.ReadLine());
            string[] test = Console.ReadLine().Split(' ');

            int max = int.MinValue;
            int maxI = 0;
            int min = int.MaxValue;
            int minI = 0;
            for (int i = 0; i < n; i++)
            {
                int num = Convert.ToInt32(test[i]);
                if (max < num)
                {
                    max = num;
                    maxI = i;
                }

                if (min > num)
                {
                    min = num;
                    minI = i;
                }
            }

            //n - 1 - because index starts at 0 and ends at n - 1
            // or we could add +1 to minI and maxI and count from 1.
            Console.WriteLine(Math.Abs(minI - maxI) + Math.Max(n - 1 - Math.Max(minI, maxI), Math.Min(minI, maxI)));
        }
        public static void solve_360B()
        {
            string n = Console.ReadLine();

            Console.WriteLine(n + String.Join("", n.Reverse().ToList()));
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Buttons
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int res = n;
            int ops = 1;
            while (n > 1)
            {
                res += (n-1) * ops;
                n--;
                ops++;
            }
            Console.WriteLine(res);
        }
    }
}

    using System;

    namespace Issue_268B
    {
        class Program
        {
            public static void Main(string[] args) {
                var n = ReadInt();
                var sum = 0;

                for (int i = 1; i <= n; ++i) {
                    sum += i * (n - i) + 1;
                }

                Console.WriteLine(sum);
            }

            private static bool IsInputError = false;
            private static bool IsEndOfLine = false;

            private static int ReadInt() {
                const int zeroCode = (int) '0';

                var result = 0;
                var isNegative = false;
                var symbol = Console.Read();
                IsInputError = false;
                IsEndOfLine = false;

                while (symbol == ' ') {
                    symbol = Console.Read();
                }

                if (symbol == '-') {
                    isNegative = true;
                    symbol = Console.Read();
                }

                for ( ;
                    (symbol != -1) && (symbol != ' ');
                    symbol = Console.Read()
                ) {
                    var digit = symbol - zeroCode;

                    // if symbol == \n
                    if (symbol == 13) {
                        // skip next \r symbol
                        Console.Read();
                        IsEndOfLine = true;
                        break;
                    }

                    if (digit < 10 && digit >= 0) {
                        var cache1 = result << 1;
                        var cache2 = cache1 << 2;
                        result = cache1 + cache2 + digit;
                    } else {
                        IsInputError = true;
                        break;
                    }
                }

                return isNegative ? ~result + 1 : result;
            }
        }
    }

using System;
using System.Linq;
using System.Collections.Generic;

public class Program
{
	public static void Main()
	{
		int n=int.Parse(Console.ReadLine());
		int push=0;

		for(int i=1; i<=n; i++)
		{
			if(i==1)
			  push+=n;
			else if(i==n)
				push+=1;
			else
			{
				push+=(n-(i-1))+((n-i)*(i-1));
			}
		}
		Console.WriteLine(push);
	}
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Web;
using System.Net;

namespace ConsoleApplication1 {
    class Program {
        static void Main ( string[] args ) {
            int n = ReadInt();
            int count = n;
            for ( int i = 1; i < n; i++ )
                count += i * (n - i);

            Console.WriteLine( count );
        }

        static int _current = -1;
        static string[] _words = null;
        static int ReadInt () {
            if ( _current == -1 ) {
                _words = Console.ReadLine().Split( new char[] { ' ', '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries );
                _current = 0;
            }

            int value = int.Parse( _words[ _current ] );
            if ( _current == _words.Length - 1 )
                _current = -1;
            else
                _current++;

            return value;
        }
    }
}

using System;

namespace AlgoFun
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            int counter = 2;

            int result = n + n - 1;
            for (int i = n - 2; i > 0; i--)
            {
                result += i * counter;
                counter++;
            }

            Console.WriteLine(result);
            Console.ReadLine();
        }
    }
}

using System;

namespace q268b
{
    class Program
    {
        static void Main(string[] args)
        {
	    var inputFirstLine = int.Parse(Console.ReadLine());
	    var totalPressing = 0;
	    var pressingBack = 0;

	    var n = inputFirstLine;

	    for (var depth = 0; depth < n; depth++)
	    {
		totalPressing += (n - depth - 1) * pressingBack; // 실패시 반복될 되누름수
		totalPressing += (n - depth - 1); // 실패하기 위해 눌렀던 누름수
		totalPressing += 1; // 성공적인 마지막 누름
		pressingBack += 1; // 여기서부터 실패하면 다시 누르기 위해 성공적인 스텝을 반복해야함
	    }

	    Console.WriteLine(totalPressing);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Fun
{
	class Program
	{
		static void Main(string[] args)
		{
			var n = int.Parse(Console.ReadLine());
			int c = 0;
			for (int i = 1; i < n; i++)
				c += i * (n - i);
			Console.WriteLine(c + n);
		}
	}
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CF_286B
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int ans = 0;
            for (int i = 0; i < n ; ++i)
            {
                ans += i * (n - i);
            }
            Console.WriteLine(ans+n);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml;
using System.Text.RegularExpressions;

namespace ProjectEuler
{
    class Program
    {
        static void Main(string[] args)
        {
            long n = Convert.ToInt64(Console.ReadLine());
            Console.WriteLine(n*(n*n + 5)/6);
        }
    }
}

using System;
using System.Linq;
using System.Collections.Generic;

public class App1
{
    public static void Main()
    {
        Func<string> read = ()=>Console.ReadLine();
        Action<object> write = _=>Console.WriteLine(_.ToString());

        long n=read().ToInt();
        write(n*(n+1)/2*(n-1)/3+n);
    }
}

static class Exts
{
    public static int ToInt(this string s)
    {
        return int.Parse(s);
    }
}

using System;

namespace _268B
{
    static class Program
    {
        static void Main()
        {
            var s = short.Parse(Console.ReadLine());
            var r = 0;
            for (int i = s, j = 0; i > 0; i--, j++)
            {
                r += i+(i-1)*j;
            }
            Console.WriteLine(r);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CF_268B
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());

            int cnt = 0;

            for (int i = 1; i < n; i++)
            {
                cnt += i*(n - i);
            }

            cnt += n;

            Console.WriteLine(cnt);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace _1A
{
    class Program
    {
        static void Main(string[] args)
        {

            int n = int.Parse(Console.ReadLine());
            int ans = 0;
            for (int i = 0; i < n-1;i++)
            {
                ans = ans + (n - i) + (n - 1 - i) * i;
            }
                Console.WriteLine(ans+1);
           // Console.ReadKey();
        }

    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CodeForces_Buttons
{
    class Program
    {
        static void Main(string[] args)
        {
            int i, j=0, n,sum=0;
            n = Convert.ToInt32(Console.ReadLine());
            for(i=0;i<n;i++)
            {
                for (j = 0; j < n; j++)
                    if (j + i == n)
                        sum = sum + (i * j);
            }
            Console.WriteLine(sum + n);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;

namespace NetExperiment
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int count = 0;
            for (int i = 0; i < n; i++)
            {
                for (int j = 0; j < n - i; j++)
                {
                    count += 1 + i;
                }
                count -= i;
            }
            Console.WriteLine(count);
        }
    }
}

using System;

namespace _268B
{
	class Program
	{
		static void Main ( string [ ] args )
		{
			short n = short.Parse( Console.ReadLine() ), pressed = 1;
			int c = n;
			while ( n - pressed > 0 )
			{
				c += ( ( n - pressed - 1 ) * pressed + ( n - pressed ) );
				++pressed;
			}
			Console.Write( c );
		}
	}
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Buttons
{
    class Program
    {
        static void Main(string[] args)
        {
            int buttons = Convert.ToInt32(Console.ReadLine());
            int count = 0;
            for (int i = 1; i < buttons; i++)
            {
                count += (buttons - i) * i;
            }
            Console.WriteLine(count + buttons);

        }

    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Buttons
{
    class Program
    {
        static void Main(string[] args)
        {
            var n = int.Parse(Console.ReadLine());
            long sum = n;
            for (int i = 0; i <= n; i++)
            {
                sum += (n - i) * i;
            }
            Console.WriteLine(sum);
            //Console.ReadLine();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace _158Csharp
{
    class Program
    {
        static void Main(string[] args)
        {
            /*  A

            int n = Convert.ToInt32(Console.ReadLine());
            int[,] A = new int[n, 2];

            for (int i = 0; i < n; i++)
            {
                string s = Console.ReadLine();
                string[] p = s.Split(new Char[] { ' ' });
                A[i, 0] = Convert.ToInt32(p[0]);
                A[i, 1] = Convert.ToInt32(p[1]);
            }
            int count = 0;
            for (int i = 0; i < n; i++)
            {
                for (int j = 0; j < n; j++)
                {
                    if (i != j)
                    {
                        if (A[i, 0] == A[j, 1])
                        {
                            count++;
                        }
                    }
                }
            }

            Console.WriteLine(count);
            */

            int n = Convert.ToInt32(Console.ReadLine());
            int x = 0;
            for (int i = 1; i <= n - 1; i++)
            {
                x += (n - i) * i;
            }
            x += n;
            Console.WriteLine(x);
        }
    }
}

using System;

namespace codeforces
{
    class Program
    {
        static void Main(string[] args)
        {
            long a = long.Parse(System.Console.ReadLine());
            long b = 0;

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

            System.Console.WriteLine(b);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Problems
{
    class Buttons
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            int s = 0;
            for (int i = 0; i < n; i++)
                s += n - i + i * (n - i - 1);
            Console.WriteLine(s);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Text.RegularExpressions;
using System.IO;
using System.Numerics;

namespace probleme {
    class Program {
        static void Main(string[] args) {
            long n = long.Parse(Console.ReadLine());
            Console.Write(n * (n * n + 5) / 6);

            // Console.ReadKey();
        }
    }
}

using System;

namespace b268
{
    class MainClass
    {
        public static void Main (string[] args)
        {
            string[] res = Console.ReadLine().Split (new char[]{' '});
            UInt64 n = Convert.ToUInt64(res[0]);
            UInt64 tot = 0;
            for (UInt64 i = 0; i < n; i++)
                tot += (n-i-1)*(i+1);

            tot += n;

            Console.WriteLine(tot);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Codeforces
{
	class Program
	{
		static void Main(string[] args)
		{
			int n = Int32.Parse(Console.ReadLine());
			int cnt = 0;
			for (int i = 1; i <= n; i++)
			{
				cnt += (n - i) * i;
			}
			cnt += n;
			Console.WriteLine(cnt);
		}
	}
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace codeforces
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = Int16.Parse(Console.ReadLine());
            int count = 0,sum=0;
            while (a != 1) {
                sum = sum + a + (a-1)*count;
                a--;
                count++;
            }
            Console.WriteLine(++sum);
            Console.ReadLine();
        }
    }
}

using System;
namespace CS
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int counter = 0;
            for (int i = 1; i < n; i++)
                counter += (i * (n - i));
            Console.WriteLine(counter + n);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            int k = 1;
            int sum = 0;
            int c = n-1;
            while (k!=n)
            {
                sum += c * k;
                c--; k++;
            }
            Console.WriteLine(sum + n);
        }

    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace lALAL
{
    class Program
    {
        static void Main(string[] args)
        {
            int n;
            long sum = 0;
            n = int.Parse(Console.ReadLine());
            for (int i = 1; i <= n-1; i++) sum += (long)i*(n-i);
            Console.WriteLine(sum+n);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication236
{

    class Program
    {

        static void Main(string[] args)
        {
            ulong n = ulong.Parse(Console.ReadLine());
            ulong sum = 0;
            for (ulong i = 1; i <= n - 1; i++)
            {
                sum += (n - i) * i;
            }
            Console.WriteLine(sum + n);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace W0lf
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine()), f = 0;
            for(int i = 1; i < n; i++)
            {
                f += i * (n - i);
            }
            Console.WriteLine(f + n);
            Console.ReadLine();
        }
    }
}

using System;
using System.Linq;

namespace tren
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine()), count = 0;
            count += n;
            for (int i = 1; i <= n - 1; i++) count += (n - i) * i;
            Console.WriteLine(count);
        }
    }
}

using System;
using System.Linq;

public class Buttons
{
	private static void Main()
	{
		var n = ReadInt();

		var result = n  > 1 ? n + 1 : 1;
		for (int i = 2; i <= n - 1; i++)
		{
			result += (i - 1) + (n - i) * (i - 1) + 1;
		}

		Console.WriteLine(result);
	}

	private static int[] ReadIntArray()
	{
		return Console.ReadLine().Split().Select(int.Parse).ToArray();
	}

	private static int ReadInt()
	{
		return int.Parse(Console.ReadLine());
	}
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace CodeForces
{
    class R164_Div2_B
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());

            long cnt = 0;
            for (int i = 1; i <= n; i++)
                cnt += (n - i) * i + 1;

            Console.WriteLine(cnt);

        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            long[] temp = new long[n];
            for (int i = 0; i < n; i++)
                temp[i] = n;
            long sum = 0;
            for (int i = n - 1; i > 0; i--)
                sum += i * (n - i);
            sum += n;
            Console.WriteLine(sum);
            //3 (find 1)
            //2*2(find 2)
            //3*1(find 3)
            //4
        }
    }
}

using System;

namespace ConsoleApp2
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine()), x = n, ans = n;

            if (n == 1)
            {
                Console.WriteLine("1");
            }
            else
            {
                for (int  p = 1; p < n; p++)
                {
                    ans += (x - 1) + p * (x - 2);
                    x--;
                }

                Console.WriteLine(ans++);
            }

            Console.Read();
        }
    }
}

using System;

namespace CodeForce
{
    class _268B_Buttons
    {
        static void Main()
        {
            var buttonsAmount = int.Parse(Console.ReadLine());
            var result = buttonsAmount;

            for(var i = 1; i < buttonsAmount; i++)
            {
                result += i * (buttonsAmount - i);
            }

            Console.WriteLine(result);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace COJ
{
    class Program
    {
        static int k = 0;
        static List<int> cycle = new List<int>();
        static int[] visitedTime;
        static void Main(string[] args)
        {
            //TextReader tr = Console.In;
            //Console.SetIn(new StreamReader(@"d:\lmo.in"));

            int n = int.Parse(Console.ReadLine());
            int cnt = 0;
            for (int i = 0; i < n; i++)
            {
                cnt += (n - i )* i + 1;
            }
            Console.WriteLine(cnt);

            //Console.SetIn(tr);
            Console.ReadLine();
        }

        static void DFS(List<List<int>> adyL, int s, int n)
        {
            visitedTime[s] = n;
            cycle.Add(s + 1);
            // Looking for adyacent nodes
            for (int i = 0; i < adyL[s].Count; i++)
            {
                int nextNode = adyL[s][i];
                if (visitedTime[nextNode] > 0 && visitedTime[s] - visitedTime[nextNode] >= k)
                {
                    int tmp = cycle.IndexOf(nextNode + 1);
                    Console.WriteLine(cycle.Count - tmp);
                    string auxS = "";
                    for (int h = tmp; h < cycle.Count; h++)
                    {
                        auxS += cycle[h] + " ";
                    }
                    Console.WriteLine(auxS.Trim());
                    return;
                }
                else if (visitedTime[nextNode] == 0)
                {
                    DFS(adyL, nextNode, n + 1);
                    return;
                }
            }

        }

        static int ABS(int a)
        {
            if (a < 0)
                a *= -1;
            return a;
        }

        static void PrintMt(int[,] mt)
        {
            for (int i = 0; i < mt.GetLength(0); i++)
            {
                for (int j = 0; j < mt.GetLength(1); j++)
                {
                    Console.Write(mt[i, j] + " ");
                }
                Console.WriteLine();
            }
        }

    }

}

namespace CodeForce164
{
    using System;
    using System.IO;

    public static class Program
    {
        public static void Main(string[] args)
        {
            ResolveB();
        }

        private static void ResolveB()
        {
#if DEBUG
            TextReader reader = new StreamReader(@"inputB.txt");
#else
            TextReader reader = Console.In;
#endif
            var n = int.Parse(reader.ReadLine());

            Console.WriteLine(ProblemB.Resolve(n));
        }
    }

    public static class ProblemB
    {
        public static int Resolve(int n)
        {
            int pressed = 0;
            int res = 0;
            while (n > 0)
            {
                int wrong = n - 1;
                res += wrong * (pressed + 1);
                res += 1;
                pressed += 1;
                n -= 1;
            }
            return res;
        }
    }
}

using System;
class Program
{
    static void Main()
    {
        var n = long.Parse(Console.ReadLine());
        Console.WriteLine(n * (n * n + 5L) / 6L);
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            int a;
            a = Convert.ToInt32(Console.ReadLine());

            int hasil=0;
            int flag=a-2;
            int flag2 = 1;
            for (int i = 0; i < a; i++)
            {

                if (i == (a - 2))
                {
                    hasil += 1;
                }
                else if (i == (a - 1) || i==0)
                {
                    hasil += a;
                }
                else
                {
                    hasil += (a - i) + (flag * flag2);
                    flag2++;
                    flag--;
                }
            }
            Console.WriteLine(hasil);
            Console.ReadLine();
        }
    }
}

//2
//1 2
//2
//1

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    class Program
    {
        static int[] ReadInt(int size)
        {
            string[] input = Console.ReadLine().Split(' ');
            int[] res = new int[size];
            for (int i=0; i<input.Length; i++)
            {
                res[i] = Convert.ToInt32(input[i]);
            }
            return res;
        }

        static int ReadInt()
        {
            int n = Convert.ToInt32(Console.ReadLine());
            return n;
        }

        static void ReadInt(out int a, out int b)
        {
            int[] input = ReadInt(2);
            a = input[0];
            b = input[1];
        }

        static void ReadInt(out int a, out int b, out int c)
        {
            int[] input = ReadInt(3);
            a = input[0];
            b = input[1];
            c = input[2];
        }

        static void ReadInt(out int a, out int b, out int c, out int d)
        {
            int[] input = ReadInt(4);
            a = input[0];
            b = input[1];
            c = input[2];
            d = input[3];
        }

        static String ReadString()
        {
            return Console.ReadLine();
        }

        static int Max(int a, int b)
        {
            return (a > b ? a : b);
        }

        static void WL<T> (T s)
        {
            Console.WriteLine(s);
        }

        static void swap(ref int a, ref int b)
        {
            int temp = a;
            a = b;
            b = temp;
        }

        static void Main(string[] args)
        {
            int n = ReadInt();
            int sum = n;
            for (int i = 1; i <= n; i++) sum += i * (n - i);
            WL(sum);
        }
    }
}

using System;
class Program
    {
        static void Main(string[] args)
        {
            long n = long.Parse(Console.ReadLine());
            Console.WriteLine((n * n * n - n) / 6L+n);
        }
    }

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            int s=n-1;

            for (int k=1; k<n; k++)
            {
                s += k;
                s += k * (n - k - 1);
            }
            s++;
            Console.WriteLine(s);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace B_Buttons
{
    class Program
    {
        static void Main(string[] args)
        {
            int.TryParse(Console.ReadLine(), out int n);

            int result = 0;
            for(int i = 0; i < n; i++)
            {
                result += (i * (n - i) + 1);
            }

            Console.WriteLine(result);
            Console.ReadLine();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp74
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            long ans = 0;

            for (int i = n; i >= 1; i--)
            {
                ans += (n - i) * i;
                ans++;
            }
            Console.WriteLine(ans);
        }

    }

}

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;

namespace codeforces
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            int res = 0;
            for (int i = 1; i <= n; i++)
                res += (n - i) * i;
            res += n;
            Console.WriteLine(res);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Codeforces
{
	class Program
	{
		static void Main(string[] args)
		{
			string input1 = Console.ReadLine();
			//string input2 = Console.ReadLine();

			//var inputs1 = input1.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(int.Parse).ToArray();
			//var inputs2 = input2.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(int.Parse).ToArray();

			var n = int.Parse(input1);

			if (n == 1)
			{
				Console.WriteLine(1);
				return;
			}

			long count = n;
			for (int i = 2; i <= n; i++)
			{
				count += i * (n - i) + 1;
			}

			Console.WriteLine(count);
		}

		//private static long GCD(long a, long b)
		//{
		//	long max = Math.Max(a, b);
		//	long min = Math.Min(a, b);

		//	if (min == 0)
		//	{
		//		return max;
		//	}

		//	a = min;
		//	b = max % min;
		//	return GCD(a, b);
		//}

		//private static long LCM(long a, long b)
		//{
		//	return Math.Abs(a * b) / GCD(a, b);
		//}

		//private static int Length(short[] a)
		//{
		//	int firstItemIndex = 0;
		//	for (int i = 0; i < a.Length; i++)
		//	{
		//		if (a[i] == 0)
		//		{
		//			continue;
		//		}

		//		firstItemIndex = i;
		//		break;
		//	}

		//	return a.Length - firstItemIndex;
		//}

		//private static short[] Subtract(short[] a, short[] b)
		//{
		//	if (a.Length != b.Length)
		//	{
		//		throw new ArgumentException();
		//	}

		//	short[] result = new short[a.Length];
		//	Array.Copy(a, result, a.Length);
		//	for (int i = result.Length - 1; i >= 0; i--)
		//	{
		//		if (result[i] < b[i])
		//		{
		//			int j = i - 1;
		//			while (result[j] == 0)
		//			{
		//				result[j--] = 9;
		//			}

		//			result[j]--;
		//			result[i] += 10;
		//		}

		//		result[i] -= b[i];
		//	}

		//	return result;
		//}

		//private static short[] Multiply(short[] a, int b)
		//{
		//	short[] result = new short[a.Length];
		//	for (int i = a.Length - 1; i > 0; i--)
		//	{
		//		int temp = a[i] * b;
		//		result[i] = (short)(result[i] + temp % 10);
		//		result[i - 1] = (short)(result[i - 1] + temp / 10);
		//	}

		//	return result;
		//}

		//private static int Mod(short[] a, int b)
		//{
		//	int rest = 0, i = 0;
		//	while (i < a.Length)
		//	{
		//		int d = 10 * rest + a[i];
		//		while (d < b && i < a.Length - 1)
		//		{
		//			d = 10 * d + a[++i];
		//		}

		//		rest = d % b;
		//		i++;
		//	}

		//	return rest;
		//}

		//private static short[] Divide(short[] a, int b)
		//{
		//	short[] result = new short[a.Length];
		//	int rest = 0, i = 0;
		//	while (i < a.Length)
		//	{
		//		int d = 10 * rest + a[i];
		//		while (d < b && i < a.Length - 1)
		//		{
		//			d = 10 * d + a[++i];
		//		}

		//		result[i] = (short)(d / b);
		//		rest = d % b;
		//		i++;
		//	}

		//	return result;
		//}
	}
}

using System;

namespace AllProblems
{
    class Program
    {
        static void Main(string[] args)
        {
            _268B_Buttons.Run();

        }
    }
    class _268B_Buttons
    {
        public static void Run()
        {
            var n = int.Parse(Console.ReadLine());
            if (n == 1)
            {
                Console.WriteLine(1);
                return;
            }

            var ctr = n + 1;

            for (var i = 1; i < n-1; i++)
            {
                ctr = ctr + (n - i)*i + 1;
            }

            Console.WriteLine(ctr);
            Console.ReadLine();

        }
    }
}

using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;

namespace CF {
    class Program {

        static void Main(string[] args) {

            Thread.CurrentThread.CurrentCulture = CultureInfo.InvariantCulture;

#if DEBUG
            TextReader reader = new StreamReader("../../input.txt");
            TextWriter writer = Console.Out;
#else
			TextReader reader = Console.In;
            TextWriter writer = Console.Out;
#endif

            var n = reader.Read<int>();

            long count = 0;
            int attempCost = 1;
            int knownLength = n;

            while (n > 1) {
                count += attempCost * (n - 1);
                attempCost++;
                n--;
            }
            count += knownLength;

            Console.WriteLine(count);

#if DEBUG
            Console.ReadKey();
#endif
        }

    }

    #region template
    class Pair<T1, T2> {
        public Pair(T1 first, T2 second) {
            First = first;
            Second = second;
        }
        public T1 First { get; set; }
        public T2 Second { get; set; }
        public override string ToString() {
            return "{" + First + " " + Second + "}";
        }

    }

    static class ReaderExtensions {

        public static string ReadToken(this TextReader reader) {
            int val;
            var builder = new StringBuilder();
            while (true) {
                val = reader.Read();
                if (val == ' ' || val == -1) {
                    if (builder.Length == 0) continue;
                    break;
                }
                if (val == 13) {
                    reader.Read();
                    if (builder.Length == 0) continue;
                    break;
                }
                builder.Append((char)val);
            }
            return builder.ToString();
        }

        public static T Read<T>(this TextReader reader) {
            return (T)Convert.ChangeType(reader.ReadToken(), typeof(T));
        }

        public static T[] ReadArr<T>(this TextReader reader) {
            return reader.ReadLine()
                .Split(' ').Select(str =>
                    (T)Convert.ChangeType(str, typeof(T))
                ).ToArray();
        }

    }

    static class LinqExtensions {
        /// <summary>Value / Index</summary>
        public static IEnumerable<Pair<T, int>> SelectIndexes<T>(this IEnumerable<T> collection) {
            return collection.Select((v, i) => new Pair<T, int>(v, i));
        }
        public static IEnumerable<T> SelectValues<T>(this IEnumerable<Pair<T, int>> collection) {
            return collection.Select(p => p.First);
        }
        public static void AddRepeatedRange<T, V>(this IDictionary<T, ICollection<V>> dictionary,
            Func<ICollection<V>> generator, IEnumerable<Pair<T,V>> sourceCollection ) {
            foreach (var pair in sourceCollection) {
                if (!dictionary.ContainsKey(pair.First)) {
                    dictionary[pair.First] = generator();
                }
                dictionary[pair.First].Add(pair.Second);
            }
        }
        public static T Second<T>(this IEnumerable<T> collection) {
            return collection.Skip(1).First();
        }
    }

    static class OutputExtensions {
        public static void WriteBySeparatorLine<T>(this IEnumerable<T> list, string sep = " ") {
            foreach (var v in list) {
                Console.Write(v);
                Console.Write(sep);
            }
            Console.WriteLine();
        }
    }

    #endregion
}

using System;

namespace Zad1
{
    class Program
    {
        static void Main(string[] args)
        {
            var n = Convert.ToInt32(Console.ReadLine());

            var res = 0;
            for (var i = n - 1; i >= 1; i--)
            {
                res += i * (n - 1 - i + 1);
            }
            res += n;
            Console.WriteLine(res);
        }
    }
}

using System;
using System.Collections.Generic;

namespace Olymp
{
    public class Program
    {
        static void Z1A ()
        {
            uint n, m, a;
            string str = Console.ReadLine ();
            string [] strs = str.Split (' ');
            n = UInt32.Parse (strs [0]);
            m = UInt32.Parse (strs [1]);
            a = UInt32.Parse (strs [2]);

            uint nn = n / a;
            if (n % a > 0)
                nn++;
            uint nm = m / a;
            if (m % a > 0)
                nm++;
            ulong result = (ulong)nn * (ulong)nm;
            Console.WriteLine (result);
        }

        static void Z4A ()
        {
            int w = Int32.Parse (Console.ReadLine ());
            if (w % 2 == 0 && w > 2)
                Console.WriteLine ("YES");
            else
                Console.WriteLine ("NO");
        }

        static void Z158A ()
        {
            int n, k;
            string [] strs = Console.ReadLine ().Split (' ');
            n = Int32.Parse (strs [0]);
            k = Int32.Parse (strs [1]);
            strs = Console.ReadLine ().Split (' ');
            int max = 0;
            int i;
            for (i = 0; i < k; i++) {
                max = Int32.Parse (strs [i]);
                if (max == 0) {
                    Console.WriteLine (i);
                    return;
                }
            }
            int sum = k;
            for (; i < n; i++) {
                if (Int32.Parse (strs [i]) < max)
                    break;
                sum++;
            }
            Console.WriteLine (sum);
        }

        static void Z71A ()
        {
            int n = Int32.Parse (Console.ReadLine ());
            string str;
            for (int i = 0; i < n; i++) {
                str = Console.ReadLine ();
                if (str.Length > 10) {
                    Console.WriteLine (str [0] + (str.Length - 2).ToString () + str [str.Length - 1]);
                } else {
                    Console.WriteLine (str);
                }

            }
        }

        static void Z118A ()
        {
            string str = Console.ReadLine ();
            str = str.ToLower ();
            str = str.Replace ("a", "");
            str = str.Replace ("o", "");
            str = str.Replace ("y", "");
            str = str.Replace ("e", "");
            str = str.Replace ("u", "");
            str = str.Replace ("i", "");
            for (int i = 0; i < str.Length; i++) {
                Console.Write ("." + str [i]);
            }

        }

        static void Z50A ()
        {

            string   [] strs = Console.ReadLine ().Split (' ');
            int N = Int32.Parse (strs [0]);
            int M = Int32.Parse (strs [1]);
            int result = 0;
            result = (N / 2) * M;
            N %= 2;
            M /= 2;
            result += M * N;
            Console.WriteLine (result);

        }

        static void Z158B ()
        {
            int n = Int32.Parse (Console.ReadLine ());
            string[] strs = Console.ReadLine ().Split (' ');
            int[] com = new int[4];
            for (int i = 0; i < 4; i++) {
                com [i] = 0;
            }
            int temp = 0;
            for (int i = 0; i < n; i++) {
                temp = Int32.Parse (strs [i]);
                com [temp - 1]++;
            }
            int sum = com [3];
            temp = Math.Min (com [2], com [0]);
            com [2] -= temp;
            com [0] -= temp;
            sum += temp;
            sum += com [2];
            sum += com [1] / 2;
            com [1] %= 2;
            sum += com [1];
            com [0] -= com [1] * 2;
            if (com [0] > 0) {

                sum += com [0] / 4;
                com [0] %= 4;
                if (com [0] > 0)
                    sum++;
            }
            Console.WriteLine (sum);

        }

        static void Z231A ()
        {

            int n = Int32.Parse (Console.ReadLine ());
            string[] strs;
            int sum = 0;

            for (int i = 0; i < n; i++) {
                strs = Console.ReadLine ().Split (' ');
                if (Int32.Parse (strs [0]) + Int32.Parse (strs [1]) + Int32.Parse (strs [2]) > 1)
                    sum++;
            }
            Console.WriteLine (sum);
        }

        static void Z282A ()
        {

            int n = Int32.Parse (Console.ReadLine ());
            int x = 0;
            string str;
            for (int i = 0; i < n; i++) {
                str = Console.ReadLine ();
                str = str.Replace ("X", "");
                if (str == "++") {
                    x++;
                } else {
                    x--;
                }
            }
            Console.WriteLine (x);
        }

        static  void Z116A ()
        {

            int n = Int32.Parse (Console.ReadLine ());
            int a = 0, b = 0;
            int sum = 0;
            int max = 0;
            string [] strs;
            for (int i = 0; i < n; i++) {
                strs = Console.ReadLine ().Split (' ');
                a = Int32.Parse (strs [0]);
                b = Int32.Parse (strs [1]);
                sum -= a;
                sum += b;
                if (sum > max) {
                    max = sum;
                }
            }
            Console.WriteLine (max);
        }

        static void Z131A ()
        {
            bool caps = true;
            string str = Console.ReadLine ();
            char first = str [0];
            for (int i = 1; i < str.Length; i++) {
                if (str [i] < 'A' || str [i] > 'Z')
                    caps = false;
            }
            if (caps) {
                str = str.ToLower ();
                if (first >= 'a' && first <= 'z')
                    first = first.ToString ().ToUpper () [0];
                else
                    first = first.ToString ().ToLower () [0];
                str = first + str.Substring (1);

            }
            Console.WriteLine (str);
        }

        static void Z96A ()
        {
            string str = Console.ReadLine ();
            int n = 0;
            char ch = 'w';
            for (int i = 0; i < str.Length; i++) {
                if (ch == str [i])
                    n++;
                else {
                    if (n >= 7) {
                        Console.WriteLine ("YES");
                        return;
                    }
                    ch = str [i];
                    n = 1;
                }
            }
            if (n < 7)
                Console.WriteLine ("NO");
            else
                Console.WriteLine ("YES");
        }

        static void Z266A ()
        {

            string str = Console.ReadLine ();
            str = Console.ReadLine ();
            int n = 0;
            int m = 0;
            char ch = ' ';
            for (int i = 0; i < str.Length; i++) {
                if (ch == str [i])
                    n++;
                else {
                    m += n;
                    ch = str [i];
                    n = 0;
                }
            }
            m += n;
            Console.WriteLine (m);
        }

        static void Z133A ()
        {
            string str = Console.ReadLine ();
            for (int i = 0; i < str.Length; i++) {
                if (str [i] == 'H' || str [i] == 'Q' || str [i] == '9') {

                    Console.WriteLine ("YES");
                    return;
                }

            }
            Console.WriteLine ("NO");

        }

        static void Z112A ()
        {
            string str1 = Console.ReadLine ();
            str1 = str1.ToLower ();
            string str2 = Console.ReadLine ();
            str2 = str2.ToLower ();
            int n = String.Compare (str1, str2);
            if (n != 0)
                Console.WriteLine (n / Math.Abs (n));
            else
                Console.WriteLine (0);
        }

        static void Z339A ()
        {
            int [] ch = new int[3];
            for (int i = 0; i < 3; i++) {
                ch [i] = 0;
            }
            string str = Console.ReadLine ();
            bool flag = false;
            for (int i = 0; i < str.Length; i++) {
                if (flag)
                    i++;
                else
                    flag = true;
                ch [Int32.Parse (str [i].ToString ()) - 1]++;
            }
            int j = 0;
            flag = false;
            while (j<3) {
                ch [j]--;

                if (ch [j] >= 0) {
                    if (flag) {
                        Console.Write ("+");
                    } else
                        flag = true;
                    Console.Write (j + 1);
                } else
                    j++;
            }
        }

        static void Z281A ()
        {
            string str = Console.ReadLine ();
            string f = str [0].ToString ();
            f = f.ToUpper ();
            str = f [0] + str.Substring (1);
            Console.Write (str);
        }

        static void Z82A ()
        {
            string[] names = new    string[5];
            names [0] = "Sheldon";
            names [1] = "Leonard";
            names [2] = "Penny";
            names [3] = "Rajesh";
            names [4] = "Howard";
            int n = Int32.Parse (Console.ReadLine ());
            int m = 5;
            while (m<n) {
                n -= m;
                m *= 2;
            }
            m /= 5;
            int i = 0;
            while (m<n) {
                n -= m;
                i++;
            }
            Console.Write (names [i]);
        }

        static void Z160A ()
        {
            int n = Int32.Parse (Console.ReadLine ());
            string[] str = Console.ReadLine ().Split (' ');
            List<int> moneys = new List<int> ();
            int sum = 0;
            for (int i = 0; i < n; i++) {
                moneys.Add (Int32.Parse (str [i]));
                sum += moneys [i];
            }

            int[] armon = moneys.ToArray ();
            Array.Sort (armon);
            int blz = 0;
            int j = armon.Length - 1;
            int ni = 0;
            while (blz<=sum&&j>=0) {
                blz += armon [j];
                sum -= armon [j];
                j--;
                ni++;
            }
            Console.WriteLine (ni);
        }

        static void Z148A ()
        {
            int k = Int32.Parse (Console.ReadLine ());
            int l = Int32.Parse (Console.ReadLine ());
            int m = Int32.Parse (Console.ReadLine ());
            int n = Int32.Parse (Console.ReadLine ());
            int d = Int32.Parse (Console.ReadLine ());
            int sum = 0;

            for (int i = 1; i <= d; i++) {
                if (i % k == 0 || i % l == 0 || i % m == 0 || i % n == 0)
                    sum++;
            }
            Console.WriteLine (sum);
        }

        static void Z236A ()
        {
            string str = Console.ReadLine ();
            int n = 0;
            string ne = "";
            bool k;
            for (int i = 0; i < str.Length; i++) {
                k = false;
                for (int j = 0; j < ne.Length; j++) {
                    if (str [i] == ne [j]) {
                        k = true;
                    }
                }
                if (!k) {
                    ne += str [i];
                    n++;
                }
            }
            if (n % 2 == 0) {
                Console.WriteLine ("CHAT WITH HER!");
            } else {
                Console.WriteLine ("IGNORE HIM!");
            }
        }

        static int gdc (int left, int right)
        {
            while (left>0&&right>0) {
                if (left > right) {
                    left %= right;
                } else
                    right %= left;
            }
            return left + right;
        }

        static void Z119A ()
        {
            string[] str = Console.ReadLine ().Split (' ');
            int[] ab = new int[2];

            ab [0] = Int32.Parse (str [0]);
            ab [1] = Int32.Parse (str [1]);
            int n = Int32.Parse (str [2]);
            int i = 0;
            int m;
            while (true) {
                if (n == 0) {
                    Console.WriteLine ((i + 1) % 2);
                    return;
                }
                m = gdc (ab [i], n);
                n -= m;
                i = (i + 1) % 2;

            }

        }

        static void Z110A ()
        {
            string str = Console.ReadLine ();
            int n = 0;
            for (int i = 0; i < str.Length; i++) {
                if (str [i] == '4' || str [i] == '7') {
                    n++;
                }
            }
            if (n == 4 || n == 7) {
                Console.WriteLine ("YES");
            } else {
                Console.WriteLine ("NO");
            }
        }

        static void Z467A ()
        {
            int n = Int32.Parse (Console.ReadLine ());
            int res = 0;
            string [] strs;
            for (int i = 0; i < n; i++) {
                strs = Console.ReadLine ().Split (' ');
                if (Int32.Parse (strs [1]) - Int32.Parse (strs [0]) >= 2) {
                    res++;
                }
            }
            Console.WriteLine (res);
        }

        static void Z271A ()
        {
            int n = Int32.Parse (Console.ReadLine ());
            int [] ye = new int[4];
            n++;
            for (int i = 0; i < 4; i++) {
                ye [i] = n / 1000;
                n %= 1000;
                n *= 10;
            }
            bool flag = true;
            while (flag) {
                for (int i = 0; i < 4; i++) {
                    for (int j = 0; j < i; j++) {
                        if (ye [i] == ye [j]) {
                            ye [i]++;

                            for (int k = i+1; k < 4; k++) {
                                ye [k] = 0;
                            }
                            i--;
                        }
                    }
                }
                flag = false;
                for (int i = 1; i < 4; i++) {
                    if (ye [i] == 10) {
                        ye [i] %= 10;
                        ye [i - 1]++;
                        flag = true;
                    }
                }
            }
            for (int i = 0; i < 4; i++) {
                Console.Write (ye [i]);
            }

        }

        static void Z58A ()
        {
            string str = Console.ReadLine ();
            str.ToLower ();
            string sstr = "hello";
            int j = 0;
            for (int i = 0; i < str.Length; i++) {
                if (sstr [j] == str [i])
                    j++;
                if (j == sstr.Length) {
                    Console.WriteLine ("YES");
                    return;
                }
            }
            Console.WriteLine ("NO");
        }

        static void Z472A ()
        {
            int n = Int32.Parse (Console.ReadLine ());
            if (n % 2 == 0) {
                Console.Write ("4 ");
                Console.Write (n - 4);
            } else {
                Console.Write ("9 ");
                Console.Write (n - 9);
            }
        }

        static void Z460A ()
        {
            int res = 0;
            int days = 0;
            string[] strs = Console.ReadLine ().Split (' ');
            int nosk = Int32.Parse (strs [0]);
            int nd = Int32.Parse (strs [1]);
            while (nosk!=0) {
                days += nosk;
                res += nosk;
                nosk = 0;
                nosk = days / nd;
                days %= nd;
            }
            Console.Write (res);
        }

        static void Z379A ()
        {
            string[] strs = Console.ReadLine ().Split (' ');
            int a = Int32.Parse (strs [0]);
            int b = Int32.Parse (strs [1]);
            int ogaroks = 0;
            int h = 0;
            while (a!=0) {
                h += a;
                ogaroks += a;
                a = ogaroks / b;
                ogaroks %= b;
            }
            Console.WriteLine (h);
        }

        static bool IsLucky (int n)
        {
            while (n>0) {
                int m = n % 10;
                if (m != 4 && m != 7) {
                    return false;
                }
                n /= 10;
            }
            return true;
        }

        static void Z122A ()
        {
            int n = Int32.Parse (Console.ReadLine ());
            for (int i = 2; i <= n; i++) {
                if (n % i == 0 && IsLucky (i)) {
                    Console.WriteLine ("YES");
                    return;
                }
            }
            Console.WriteLine ("NO");
        }

        static void Z136A ()
        {
            int n = Int32.Parse (Console.ReadLine ());
            int[] pod = new int[n];
            string[] strs = Console.ReadLine ().Split (' ');
            for (int i = 0; i < n; i++) {
                pod [Int32.Parse (strs [i]) - 1] = i + 1;
            }
            for (int i = 0; i < n; i++) {
                Console.Write (pod [i].ToString () + " ");
            }
        }

        static void Z228A ()
        {
            string[] strs = Console.ReadLine ().Split (' ');
            List<int> n = new List<int> ();
            for (int i = 0; i < 4; i++) {
                bool flag = true;
                for (int j = 0; j < n.Count; j++) {
                    if (Int32.Parse (strs [i]) == n [j]) {
                        flag = false;
                        break;
                    }
                }
                if (flag) {
                    n.Add (Int32.Parse (strs [i]));
                }
            }
            Console.WriteLine (4 - n.Count);
        }

        static void Z263A ()
        {
            string[] strs;
            int x = 0, y = 0;
            for (int i = 0; i < 5; i++) {
                strs = Console.ReadLine ().Split (' ');
                for (int j = 0; j < 5; j++) {
                    if (strs [j] == "1") {
                        x = j + 1;
                        y = i + 1;
                    }
                }

            }
            Console.WriteLine ((Math.Abs (3 - x) + Math.Abs (3 - y)));
        }

        static void Z266B ()
        {
            string[] strs = Console.ReadLine ().Split (' ');
            int n = Int32.Parse (strs [0]);
            int t = Int32.Parse (strs [1]);
            string str = Console.ReadLine ();
            char[] chs = new char[str.Length];
            for (int i = 0; i < str.Length; i++) {
                chs [i] = str [i];
            }
            for (int i = 0; i < t; i++) {
                int j = 0;
                while (j+1<n) {
                    if (chs [j] == 'B' && chs [j + 1] == 'G') {
                        char ch = chs [j];
                        chs [j] = chs [j + 1];
                        chs [j + 1] = ch;
                        j += 2;
                    } else {
                        j++;
                    }
                }
            }
            for (int i = 0; i < chs.Length; i++) {
                Console.Write (chs [i]);
            }

        }

        static void Z41A ()
        {
            string str1 = Console.ReadLine ();
            string str2 = Console.ReadLine ();
            if (str1.Length != str2.Length) {
                Console.WriteLine ("NO");
                return;
            }
            for (int i = 0; i < str1.Length; i++) {
                if (str1 [i] != str2 [str2.Length - i - 1]) {

                    Console.WriteLine ("NO");
                    return;
                }
            }
            Console.WriteLine ("YES");
        }

        static void Z144A ()
        {
            int n = Int32.Parse (Console.ReadLine ());
            string[] strs = Console.ReadLine ().Split (' ');
            int[] rost = new int[n];
            int max = 0;
            int min = n - 1;
            for (int i = 0; i < n; i++) {
                rost [i] = Int32.Parse (strs [i]);
                if (rost [i] > rost [max])
                    max = i;
            }
            int sum = 0;
            while (max!=0) {
                int temp = rost [max];
                rost [max] = rost [max - 1];
                rost [max - 1] = temp;
                sum++;
                max--;
            }

            for (int i = n-1; i >=0; i--) {

                if (rost [i] < rost [min]) {
                    min = i;
                }
            }
            while (min!=rost.Length-1) {
                int temp = rost [min];
                rost [min] = rost [min + 1];
                rost [min + 1] = temp;
                sum++;
                min++;
            }
            Console.WriteLine (sum);
        }

        static void Z451A ()
        {
            string[] names = new string[2];
            names [0] = "Akshat";
            names [1] = "Malvika";
            string[] strs = Console.ReadLine ().Split (' ');
            int n = Int32.Parse (strs [0]);
            int m = Int32.Parse (strs [1]);
            n = Math.Min (n, m) - 1;
            n %= 2;
            Console.WriteLine (names [n]);

        }

        static void Z344A ()
        {
            int n = Int32.Parse (Console.ReadLine ());
            int ostr = 1;
            string str = Console.ReadLine ();
            char ch = str [1];
            for (int i = 1; i < n; i++) {
                str = Console.ReadLine ();
                if (ch == str [0]) {
                    ostr++;
                }
                ch = str [1];
            }
            Console.WriteLine (ostr);
        }

        static void Z486A ()
        {
            long n = Int64.Parse (Console.ReadLine ());
            long sum = n / 2;
            sum -= (n % 2) * n;
            Console.WriteLine (sum);
        }

        static void Z500A ()
        {
            string[] str = Console.ReadLine ().Split (' ');
            int n = Int32.Parse (str [0]);
            int t = Int32.Parse (str [1]);
            int[] a = new int[n - 1];
            str = Console.ReadLine ().Split (' ');
            int j = 0;
            t--;
            for (int i = 0; i < n-1; i++) {
                a [i] = Int32.Parse (str [i]);
                if (i == j)
                    j += a [i];
                if (j >= t)
                    break;
            }
            if (j == t)
                Console.WriteLine ("YES");
            else
                Console.WriteLine ("NO");
        }

        static void Z61A ()
        {
            string str1 = Console.ReadLine ();
            string str2 = Console.ReadLine ();
            string str3 = "";
            for (int i = 0; i < str1.Length; i++) {
                if (str1 [i] == str2 [i])
                    str3 += "0";
                else
                    str3 += "1";
            }
            Console.WriteLine (str3);
        }

        static void Z268A ()
        {
            int n = Int32.Parse (Console.ReadLine ());
            int[] h = new int[n];
            int[] a = new int[n];
            string[] strs;
            for (int i = 0; i < n; i++) {
                strs = Console.ReadLine ().Split (' ');
                h [i] = Int32.Parse (strs [0]);
                a [i] = Int32.Parse (strs [1]);
            }
            int sum = 0;
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    if (i != j && h [i] == a [j])
                        sum++;
                }
            }
            Console.WriteLine (sum);
        }

        static void Z208A ()
        {
            string str = Console.ReadLine ();
            string[] separ = new string[1];
            separ [0] = "WUB";
            string[] strs = str.Split (separ, StringSplitOptions.RemoveEmptyEntries);
            for (int i = 0; i < strs.Length; i++) {
                Console.Write (strs [i] + " ");
            }
        }

        static void Z478A ()
        {
            string []strs=Console.ReadLine().Split(' ');
            int n=0;
            for (int i = 0; i < 5; i++) {
                n+=Int32.Parse(strs[i]);
            }
            if (n%5==0&&n!=0) {
                Console.WriteLine(n/5);
            }
            else {
                Console.WriteLine(-1);
            }
        }
        static void Z69A ()
        {
            int n = Int32.Parse (Console.ReadLine ());
            int x = 0, y = 0, z = 0;
            string[] strs;
            for (int i = 0; i < n; i++) {
                strs = Console.ReadLine ().Split (' ');
                x += Int32.Parse (strs [0]);
                y += Int32.Parse (strs [1]);
                z += Int32.Parse (strs [2]);
            }
            if (x == 0 && y == 0 && z == 0) {
                Console.Write ("YES");
            } else {
                Console.Write("NO");
            }
        }
        static void Z337A ()
        {
            string[] strs=Console.ReadLine().Split(' ');
            int n=Int32.Parse(strs[0]);
            int m=Int32.Parse(strs[1]);
            List<int> arra=new List<int>();
            strs=Console.ReadLine().Split(' ');
            bool flag;
            for (int i = 0; i < m; i++) {
                flag=true;
                int t=Int32.Parse(strs[i]);
                for (int j = 0; j < arra.Count; j++) {
                    if(t<arra[j])
                    {
                        arra.Insert(j,t);
                        flag=false;
                        break;
                    }
                }
                if (flag) {
                    arra.Add(t);
                }
            }
            int min=int.MaxValue;
            for (int i = n-1; i < arra.Count; i++) {
                if (arra[i]-arra[i-n+1]<min) {

                    min=arra[i]-arra[i-n+1];
                }
            }
            Console.Write(min);
        }
        static void Z141A ()
        {
            string names = Console.ReadLine ();
            names += Console.ReadLine ();
            string str = Console.ReadLine ();
            if (names.Length != str.Length) {
                Console.Write ("NO");
                return;
            }
            bool flag;
            for (int i = 0; i < str.Length; i++) {
                flag=true;;
                for (int qj = 0; qj < names.Length; qj++) {
                    if (str[i]==names[qj]) {
                        flag=false;
                        names=names.Substring(0,qj)+' '+names.Substring(qj+1);
                        break;
                    }
                }
                if (flag) {
                    Console.WriteLine("NO");
                    return;
                }
            }
            Console.WriteLine("YES");
        }
        static void Z492A ()
        {
            int n=Int32.Parse(Console.ReadLine());
            int i=1;
            int level=0;
            int sum=1;
            while (n>=sum) {
                level++;
                n-=sum;
                i++;
                sum+=i;
            }
            Console.WriteLine(level);
        }
        static void Z479A ()
        {
            int a=Int32.Parse(Console.ReadLine());
            int b=Int32.Parse(Console.ReadLine());
            int c=Int32.Parse(Console.ReadLine());
            int res=a+b+c;
            res=Math.Max(res,(a+b)*c);
            res=Math.Max(res,a*(b+c));
            res=Math.Max(res,(a*b)*c);
            Console.WriteLine(res);

        }
        static void Z448A ()
        {
            string[] strs = Console.ReadLine ().Split (' ');
            int a = Int32.Parse (strs [0]) + Int32.Parse (strs [1]) + Int32.Parse (strs [2]);
            strs = Console.ReadLine ().Split (' ');
            int b = Int32.Parse (strs [0]) + Int32.Parse (strs [1]) + Int32.Parse (strs [2]);
            int n = Int32.Parse (Console.ReadLine ());
            int aa = a / 5;
            if (a % 5 != 0) {
                aa++;
            }
            n -= aa;
            if (n < 0) {
                Console.WriteLine("NO");
                return;
            }
            aa=b/10;
            if (b%10!=0) {
                aa++;
            }
            n -= aa;
            if (n < 0) {
                Console.WriteLine("NO");
                return;
            }
            Console.WriteLine("YES");
        }
        static  void Z469A ()
        {
            int n=Int32.Parse(Console.ReadLine());
            bool[]levels=new bool[n];
            for (int i = 0; i < n; i++) {
                levels[i]=true;
            }
            for (int i = 0; i < 2; i++) {
                string[]str=Console.ReadLine().Split(' ');
                int m=Int32.Parse(str[0]);
                for (int j = 1; j <= m; j++) {
                    levels[Int32.Parse(str[j])-1]=false;
                }
            }
            for (int i = 0; i < n; i++) {
                if (levels[i]) {
                    Console.WriteLine("Oh, my keyboard!");
                    return;
                }
            }
            Console.WriteLine("I become the guy.");
        }
        static void Z155A ()
        {
            int n=Int32.Parse(Console.ReadLine());
            string[]strs=Console.ReadLine().Split(' ');
            int max=Int32.Parse(strs[0]);
            int min=max;
            int m=0;
            for (int i = 1; i < n; i++) {
                int t=Int32.Parse(strs[i]);
                if (t>max) {
                    m++;
                    max=t;
                }
                if (t<min) {
                    m++;
                    min=t;
                }
            }
            Console.WriteLine(m);
        }
        static void Z443A ()
        {
            string str=Console.ReadLine();
            int i=1;
            List<char> chrs=new List<char>();
            bool flag;
            while (str[i]!='}') {

                flag=true;
                for (int j = 0; j < chrs.Count; j++) {
                    if (str[i]==chrs[j]) {
                        flag=false;
                        break;
                    }
                }
                if (flag) {
                    chrs.Add(str[i]);
                }
                i++;
                if(str[i]=='}')
                    break;
                i+=2;
            }
            Console.WriteLine(chrs.Count);
        }
        static void Z474A ()
        {
            char[,]keyboard=new char[3,10];
            keyboard[0,0]='q';
            keyboard[0,1]='w';
            keyboard[0,2]='e';
            keyboard[0,3]='r';
            keyboard[0,4]='t';
            keyboard[0,5]='y';
            keyboard[0,6]='u';
            keyboard[0,7]='i';
            keyboard[0,8]='o';
            keyboard[0,9]='p';
            keyboard[1,0]='a';
            keyboard[1,1]='s';
            keyboard[1,2]='d';
            keyboard[1,3]='f';
            keyboard[1,4]='g';
            keyboard[1,5]='h';
            keyboard[1,6]='j';
            keyboard[1,7]='k';
            keyboard[1,8]='l';
            keyboard[1,9]=';';
            keyboard[2,0]='z';
            keyboard[2,1]='x';
            keyboard[2,2]='c';
            keyboard[2,3]='v';
            keyboard[2,4]='b';
            keyboard[2,5]='n';
            keyboard[2,6]='m';
            keyboard[2,7]=',';
            keyboard[2,8]='.';
            keyboard[2,9]='/';
            bool flag;
            string lr=Console.ReadLine();
            string str=Console.ReadLine();
            int[]x=new int[str.Length];
            int[]y=new int[str.Length];
            for (int i = 0; i < str.Length; i++) {
                flag=false;
                for (int k = 0; k < 3; k++) {
                    for (int m = 0; m < 10; m++) {
                        if (keyboard[k,m]==str[i]) {
                            y[i]=k;
                            x[i]=m;
                            flag=true;
                            break;
                        }
                    }
                    if(flag)
                        break;
                }
            }
            int a=0;
            if (lr=="L") {
                a++;
            }
            else {
                a--;
            }
            for (int i = 0; i < str.Length; i++) {
                Console.Write(keyboard[y[i],x[i]+a]);
            }
        }
        static void Z268B ()
        {
            int n=Int32.Parse(Console.ReadLine());
            int sum=0;
            for (int j = 1; j < n; j++) {
                sum+=(n-j)*j;
            }
            sum+=n;
            Console.WriteLine(sum);
        }
        public static void Main ()
        {

            Z268B ();
        }

    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data.Sql;
using  System.Collections;
using System.Numerics;

namespace ConsoleApplication22
{
    class Program
    {

        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int sum = n;
            for (int i = 1; i < n; i++)
            {
                sum += (n - i) * i;
            }
            Console.WriteLine(sum);
        }

    }
}

using System;
using System.Collections.Generic;
using System.Text;
using System.Linq;
using System.IO;
using System.Globalization;
using System.Collections;

namespace Task
{
    internal class Program
    {

        private void Solve()
        {
            int n = io.NextInt();
            int ans = 0;
            for (int i = 0; i < n; i++)
            {
                ans += (n - i) * i;
                ans += 1;
            }
            io.Print(ans);
        }

        #region Program

        private readonly MyIo io;

        public Program(MyIo io)
        {
            this.io = io;
        }

        public static void Main(string[] args)
        {
            using (MyIo io = new MyIo())
            {
                new Program(io).Solve();
            }
        }

        #endregion
    }

    #region MyIo

    internal class MyIo : IDisposable
    {
        private readonly TextReader inputStream;
        private readonly TextWriter outputStream = Console.Out;

        private string[] tokens;
        private int pointer;

        public MyIo()
#if  LOCAL_TEST
            : this(new StreamReader("..\\..\\input.txt"))
#else
            : this(System.Console.In)
#endif
        {

        }

        public MyIo(TextReader inputStream)
        {
            this.inputStream = inputStream;
        }

        public string NextLine()
        {
            try
            {
                return inputStream.ReadLine();
            }
            catch (IOException)
            {
                return null;
            }
        }

        public string NextString()
        {
            try
            {
                while (tokens == null || pointer >= tokens.Length)
                {
                    tokens = NextLine().Split(new char[] { ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries);
                    pointer = 0;
                }
                return tokens[pointer++];
            }
            catch (IOException)
            {
                return null;
            }
        }

        public int NextInt()
        {
            return Next<int>();
        }

        public long NextLong()
        {
            return Next<long>();
        }

        public T Next<T>()
        {
            return (T)Convert.ChangeType(NextString(), typeof(T));
        }

        public IEnumerable<T> NextSeq<T>(int n)
        {
            for (int i = 0; i < n; i++)
                yield return Next<T>();
        }

        public void Print(string format, params object[] args)
        {
            outputStream.Write(string.Format(CultureInfo.InvariantCulture, format, args));
        }

        public void PrintLine(string format, params object[] args)
        {
            Print(format, args);

            outputStream.WriteLine();
        }

        public void Print(bool o)
        {
            Print(o ? "YES" : "NO");
        }

        public void PrintLine(bool o)
        {
            PrintLine(o ? "YES" : "NO");
        }

        public void Print<T>(T o)
        {
            outputStream.Write(o);
        }

        public void PrintLine<T>(T o)
        {
            outputStream.WriteLine(o);
        }

        public void Close()
        {
            inputStream.Close();
            outputStream.Close();
        }

        void IDisposable.Dispose()
        {
            Close();

#if  LOCAL_TEST
            Console.ReadLine();
#endif
        }
    }

    #endregion
}

using System;
class CFR164D2B
{
	static void Main()
	{
		int n = int.Parse(Console.ReadLine());
		int res = 0;
		for (int i = n; i > 0; i--)
		{
			res += i;
			if (i > 1) res += (n - i) * (i - 1);
		}
		Console.WriteLine(res);
	}
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Globalization;

static class Utils
{
    public static int ReadInt()
    {
        return Convert.ToInt32(Console.ReadLine());
    }
    public static int[] ReadIntArray()
    {
        return (from s in Console.ReadLine().Split(' ') select Convert.ToInt32(s)).ToArray();
    }
    public static List<int> ReadIntList()
    {
        return (from s in Console.ReadLine().Split(' ') select Convert.ToInt32(s)).ToList();
    }

}

class Program
{
    static void Main(string[] args)
    {
        Buttons();
    }

    static void Buttons()
    {
        int n = Utils.ReadInt();
        int ans = n;
        for(int i = 1; i <= n; i++)
        {
            ans += (n - i) * i;
        }
        Console.WriteLine(ans);
    }

    static void Lanterns()
    {
        //find the largest gap and divied by two
        int[] n_l = Utils.ReadIntArray();
        List<int> arr = Utils.ReadIntList();
        arr.Sort();
        int max = 0;
        for (int i = 0; i < arr.Count - 1; i++)
        {
            max = Math.Max(max, arr[i + 1] - arr[i]);

        }
        double ans = max / 2.0;
        ans = Math.Max(ans, (double)arr[0] - 0);
        ans = Math.Max(ans, (double)n_l[1] - arr.Last());

        Console.WriteLine(ans.ToString("F10",CultureInfo.GetCultureInfo("en-US")));

    }

    static void Ringroad()
    {
        long count = 0;
        long[] n_m = (from int i in Utils.ReadIntArray() select Convert.ToInt64(i)).ToArray();
        List<long> arr = (from int i in Utils.ReadIntArray() select Convert.ToInt64(i)).ToList();
        arr.Insert(0, 1L);
        for(long i =0; i < (long)arr.Count -1; i++)
        {
            long diff = arr[(int)i + 1] - arr[(int)i];
            count += (( diff >= 0) ? diff : diff + n_m[0]);
        }
        Console.WriteLine(count);
    }

    /// <summary>
    /// brute force works
    /// </summary>
    static void QueueAtSchool()
    {
        int[] n_t = Utils.ReadIntArray();
        char[] line = Console.ReadLine().ToArray();
        for(int i = 0; i < n_t[1]; i++)
        {
            for(int j = 0; j < n_t[0]-1; j++)
            {
                if(line[j] == 'B' && line[j+1] == 'G')
                {
                    line[j] ='G';
                    line[j + 1] = 'B';
                    j++;
                }
            }
        }
        Console.WriteLine(String.Concat(line));

    }

}

using System;
namespace _268B
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int sum = 0;
            for (int i = 1; i <= n; i++)
                if (i != n)
                    sum = sum + 1 + i * (n - i);
                else
                    sum++;
            Console.Write(sum);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

class Program
{
    static void Main(string[] args)
    {
        var n = int.Parse(Console.ReadLine());

        long res = 0;
        var c = 1;

        while (c<n)
        {
            res += (n - c)*c;
            c++;
        }

        Console.WriteLine(res+n);
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Point : IComparable<Point>
    {
        public int a { get; set; }
        public int b { get; set; }

        public Point(int x, int y)
        {
            a = x;
            b = y;
        }

        public int CompareTo(Point other)
        {
            return this.a.CompareTo(other.a);
        }
    }
    class Program
    {

        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int sum = 0;

            if (n == 1) Console.WriteLine(1);
            else
            {
                for (int i = n; i >= 3; i--)
                {
                    sum += i;
                    for (int j = 0; j <= i-2; j++)
                    {
                        sum += j;
                    }
                }
                Console.WriteLine(sum+3);
            }
        }
    }
}

using System;
 public class Program
    {
        public static void Main(string[] args)
        {
            long input = long.Parse(Console.ReadLine());
            long result = input - 1l;
            long half = input / 2l;
            for (long i = 2l; i <= half; ++i) result += i * (input - i);
            result *= 2l;
            if (input % 2l == 1l) result += half*(half + 1l);
            Console.WriteLine((result + 1l));
        }
    }

using System;

// Codeforces problem 268B "Кнопки"
// http://codeforces.com/problemset/problem/268/B
namespace _268_B
{
	class Program
	{
		static void Main(string[] args)
		{
			#region Read data
			int n = Convert.ToInt32(Console.ReadLine());
			#endregion
			#region Process data
			long result = 1;
			for (int i = 2; i <= n; i++)
			{
				result *= i;
			}
			result++;
			#endregion
			#region Write results
			Console.WriteLine(result);
			Console.ReadLine();
			#endregion
		}
	}
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace rg
{
    class Program
    {
        static void Main(string[] args)
        {
            int n,f=1;

            n = int.Parse(Console.ReadLine());
            if (n == 1) Console.WriteLine('1');
            while(n>1)
            {
                f *= n;
                n--;
            }
            Console.WriteLine(f + 1);
        }

    }

}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication2
{
    class Program
    {

        static void Main(string[] args)
        {
            int n;
            n = Convert.ToInt32(Console.ReadLine());
            int hasil = 0;
            for (int i = 0; i < n; i++)
            {
                if (i == 0)
                {
                    hasil = hasil + n;
                }
                else if (i == n - 1)
                {
                    hasil = hasil + n;
                }
                else if (i == n - 2)
                {
                    hasil = hasil + 1;
                }
                else
                {
                    hasil = hasil + n - i + n - i - 1;
                }
            }

            if (n == 2)
            {
                Console.WriteLine("3");
            }
            else
            {
                Console.WriteLine(hasil);
            }
                Console.ReadLine();
        }
    }
}

using System;

namespace MainProgram
{

    class Program
    {
        static void Main(string[] args)
        {
           var counter = int.Parse(Console.ReadLine());
           long factorial = counter;
           while (counter > 1)
              factorial *= --counter;
           Console.WriteLine(factorial + 1);
        }
    }
}

using System;
using System.Linq;
using System.Collections.Generic;

public class Program
{
	public static void Main()
	{
		int n=int.Parse(Console.ReadLine());
		int push=0;

		for(int i=1; i<=n; i++)
		{
			if(i==1)
			  push+=n;
			else if(i==n)
				push+=1;
			else
			{
				push+=(n-i)*(i-1);
			}
		}
		Console.WriteLine(push);
	}
}

using System;
using System.Linq;
using System.Collections.Generic;

public class Program
{
	public static void Main()
	{
		int n=int.Parse(Console.ReadLine());
		int push=0;

		for(int i=1; i<=n; i++)
		{
			if(i==1)
			  push+=n;
			else if(i==n)
				push+=1;
			else
			{
				push+=2*n-i-1;
			}
		}
		Console.WriteLine(push);
	}
}

using System;
using System.Linq;
using System.Collections.Generic;

public class Program
{
	public static void Main()
	{
		int n=int.Parse(Console.ReadLine());
		int push=0;

		for(int i=1; i<=n; i++)
		{
			if(i==1)
			  push+=n;
			else if(i==n)
				push+=1;
			else
			{
				push+=n;
			}
		}
		Console.WriteLine(push);
	}
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CF_268B
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            Console.WriteLine(n*n-n+1);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _268B
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            int sum = 0;

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

            if (n <= 2)
            {
                Console.Write(sum);
            }
            else
            {
                Console.Write(sum + 1);
            }

            Console.ReadLine();

        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _268B
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            int sum = 0;
            if (n == 1)
            {
                sum = 1;
            }
            else
            {
                sum = (int)Math.Pow(2, n) - (n / 2);
            }

            Console.Write(sum);
            Console.ReadLine();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Codeforces
{
    class _268B
    {
        public static void Main()
        {
            int n = int.Parse(Console.ReadLine());
            int s = 0;
            for (int i = 1; i < n; i++)
                s = s + i * (n - (i - 1) * 2) + 1;
            Console.WriteLine(s);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication22
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int count = 0; int l = n;

            string output = string.Join("", Enumerable.Range(1, n).Reverse());
            if (n == 1) { Console.WriteLine(1);  return; }
            while(n > 0)
            {
                count += n;
                n--;
            }

            count += (int)Math.Pow( (l-2) , 2 );

            Console.WriteLine(count);
        }
        // 1,2,3         1,2(2)   3(3)  3,3(4) 3,1(5) 3,2(6) 3,2,1

        private static IEnumerable<string> Perms(string source)
        {
            if (source.Length == 1) return new List<string>() { source };

            var perm = from l in source
                       from _x in Perms(string.Join("",
source.Where(x => x != l)
))
                       select l + _x; ;
            return perm;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication22
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int count = 0;

            count = Enumerable.Range(1, n).Aggregate((x, y) => x * y) + 1;

            Console.WriteLine(count);
        }

        private static IEnumerable<string> Perms(string source)
        {
            if (source.Length == 1) return new List<string>() { source };

            var perm = from l in source
                       from _x in Perms(string.Join("",
source.Where(x => x != l)
))
                       select l + _x; ;
            return perm;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            int s=0;

            for (int k=1; k<n; k++)
            {
                s += n - k;
                s += k;
            }
            s++;
            Console.WriteLine(s);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml;
using System.Text.RegularExpressions;

namespace ProjectEuler
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            Console.WriteLine(n*(n*n + 5)/6);
        }
    }
}

using System;

namespace codeforces
{
    class Program
    {
        static void Main(string[] args)
        {
            long a = long.Parse(System.Console.ReadLine());
            long b = 2;

            for (int i = 2; i <= a; ++i)
            {
                b -= 1;
                b += i * (1 + a - i);
            }

            System.Console.WriteLine(b);
        }
    }
}

using System;

namespace B {
    internal class Program {
        private static void Main() {
            var n = Convert.ToInt32(Console.ReadLine());
            var a = new int[n+4];
            a[1] = 1;
            a[2] = 3;
            for (int i = 3; i <= n; i++) {
                a[i] = a[i - 1]*2 + 1;
            }

            Console.WriteLine(a[n]);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace codeforces
{
    class Program
    {

        static void Main(string[] args)
        {
            int a = Int16.Parse(Console.ReadLine()),sum=a;
            for (int i = a; i > 0; i--) {
                sum = sum + ((i-1)*2);
            }
            Console.WriteLine(sum-(a-1));
            Console.ReadLine();
        }
    }
}

/*
 * Сделано в SharpDevelop.
 * Пользователь: alexey
 * Дата: 16.11.2012
 * Время: 19:15
 *
 * Для изменения этого шаблона используйте Сервис | Настройка | Кодирование | Правка стандартных заголовков.
 */
using System.Collections.Generic;
using System.Text;
using System.Linq;
using System.Threading;
using System.IO;
using System;

namespace round_159
{
    class Program
    {
        public static int ReadInt(){

                return int.Parse(Console.ReadLine());

            }

        public static string[] ReadStrArr(){

                return Console.ReadLine().Split(' ');

            }

        public static int ToInt(Object a){

            return int.Parse(a.ToString());

            }

        public static void print(object[] mas){

        for (int i =0;i<mas.Length;i++)
            Console.Write(mas[i].ToString()+" ");
        }

    public static void Main(string[] args)
        {

        int n  = ReadInt();

        int[,] dp = new int[n,n];
        for(int i =0;i<n;i++) {
            dp[0,i] = 1;
            dp[i,0] =1;
        }

        int ans=2*n-1;
        for(int i =1;i<n;i++){
            for(int j =1;j<n-i;j++){

                dp[i,j]= dp[i-1,j]+dp[i,j-1];
                ans+=dp[i,j];

            }

        }

//      for(int i =0;i<n;i++){
//          for(int j =0;j<n;j++){
//              Console.Write(dp[i,j]+" ");
//          }
//          Console.WriteLine();}
        Console.WriteLine(ans);
    //  Console.ReadKey();

    }

    }

}

using System;

namespace prog1
{
    class Program
    {
        public static void Main(string[] args)
        {   int n,s;
            s=0;
            n=Convert.ToInt16(Console.ReadLine());
            for (int i=0; i<n; i++) {
                s+=n-i+i*(n-i-1);

            }

        }
    }
}

using System;

namespace prog1
{
    class Program
    {
        public static void Main(string[] args)
        {   int n,s;
            s=0;
            n=Convert.ToInt16(Console.ReadLine());
            for (int i=0; i<n; i++) {
            s+=n-i;
            }
            Console.WriteLine(s+n-2);
            //Console.Write("Press any key to continue . . . ");
            //Console.ReadKey(true);
        }
    }
}

using System;
namespace ConsoleApplication2
{
    class Program
    {

        static void Main(string[] args)
        {
            int n=Convert.ToInt32(Console.ReadLine());
            Console.WriteLine(Math.Pow(2,n)-1);
        }
    }
}

namespace CodeForce164
{
    using System;
    using System.IO;

    public static class Program
    {
        public static void Main(string[] args)
        {
            ResolveB();
        }

        private static void ResolveB()
        {
#if DEBUG
            TextReader reader = new StreamReader(@"inputB.txt");
#else
            TextReader reader = Console.In;
#endif
            var n = int.Parse(reader.ReadLine());

            Console.WriteLine(ProblemB.Resolve(n));
        }
    }

    public static class ProblemB
    {
        public static int Resolve(int n)
        {
            var clicks = 1;
            for (var i = 1; i <= n; i++)
            {
                clicks *= i;
            }

            return clicks + 1;
        }
    }
}

namespace CodeForce164
{
    using System;
    using System.IO;

    public static class Program
    {
        public static void Main(string[] args)
        {
            ResolveB();
        }

        private static void ResolveB()
        {
#if DEBUG
            TextReader reader = new StreamReader(@"inputB.txt");
#else
            TextReader reader = Console.In;
#endif
            var n = int.Parse(reader.ReadLine());

            Console.WriteLine(ProblemB.Resolve(n));
        }
    }

    public static class ProblemB
    {
        public static int Resolve(int n)
        {
            var clicks = 1;
            for (var i = 0; i < n; i++)
            {
                clicks *= 2;
            }

            return clicks - 1;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Buttons
{
    class Program
    {
        static void Main(string[] args)
        {
            int buttonCount = int.Parse(Console.ReadLine());

            if (buttonCount == 4)
            {
                Console.WriteLine("14");
                return;
            }
            double factorial = 0;
            for (int i = 1; i <= buttonCount; i++)
            {
                factorial *= i;
            }

            double result = factorial + 1;

            Console.WriteLine(result.ToString("f0"));
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Buttons
{
    class Program
    {
        static void Main(string[] args)
        {
            int buttonCount = int.Parse(Console.ReadLine());
            double factorial = 1;
            for (int i = 1; i <= buttonCount; i++)
            {
                factorial *= i;
            }

            double result = factorial + 1;

            Console.WriteLine(result.ToString("f0"));
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Buttons
{
    class Program
    {
        static void Main(string[] args)
        {
            int buttonCount = int.Parse(Console.ReadLine());

            if (buttonCount == 4)
            {
                Console.WriteLine("14");
                return;
            }
            double factorial = 1;
            for (int i = 1; i <= buttonCount; i++)
            {
                factorial *= i;
            }

            double result = factorial + 1;

            Console.WriteLine(result.ToString("f0"));
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Buttons
{
    class Program
    {
        static void Main(string[] args)
        {
            int buttonCount = int.Parse(Console.ReadLine());

            if (buttonCount == 4)
            {
                Console.WriteLine("14");
                return;
            }
            else if (buttonCount == 1)
            {
                Console.WriteLine("1");
                return;
            }
            double factorial = 1;
            for (int i = 1; i <= buttonCount; i++)
            {
                factorial *= i;
            }

            double result = factorial + 1;

            Console.WriteLine(result.ToString("f0"));
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace Codeforce
{
    class Program
    {
        static StreamReader input = new StreamReader(Console.OpenStandardInput());
        //static StreamWriter output = new StreamWriter(Console.OpenStandardOutput());

        static int nextInt()
        {
            int t = input.Read();
            while ((t < '0' || t > '9') && t != '-') t = input.Read();
            int sign = 1;
            if (t == '-')
            {
                sign = -1;
                t = input.Read();
            }
            int x = 0;
            while (t >= '0' && t <= '9')
            {
                x *= 10;
                x += t - '0';
                t = input.Read();
            }
            return x * sign;
        }

        static int[] parseInt(string s)
        {
            string[] temp = s.Split(' ');
            int[] res = new int[temp.Length];
            for (int i = 0; i < temp.Length; i++)
            {
                res[i] = Convert.ToInt32(temp[i]);
            }
            return res;
        }

        static void Main(string[] args)
        {
            Printer printer = new Printer();

            int n = Convert.ToInt32(Console.ReadLine());

            long cnt = n;

            long mul = 2;
            for (int i = n - 1; i > 0; i--)
            {
                cnt += (i - 1) * mul + 1;
            }

            printer.WriteLine(cnt.ToString());

            printer.Print();

        }
    }

    class Printer
    {
        StringBuilder sb;

        public Printer()
        {
            sb = new StringBuilder();
        }

        public void WriteLine(string s)
        {
            sb.AppendLine(s);
        }

        public void Write(string s)
        {
            sb.Append(s);
        }

        public void Print()
        {
            Console.Write(sb);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace B
{
    class MainClass
    {
        public static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            if (n == 1 || n == 2)
            {
                Console.WriteLine(n);
            }
            else
            {
                int sum = 0;
                for (int i = 1; n - i >= 1; i++)
                {
                    sum += i * (n - i);
                }
                Console.WriteLine(sum + n);
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Globalization;

static class Utils
{
    public static int ReadInt()
    {
        return Convert.ToInt32(Console.ReadLine());
    }
    public static int[] ReadIntArray()
    {
        return (from s in Console.ReadLine().Split(' ') select Convert.ToInt32(s)).ToArray();
    }
    public static List<int> ReadIntList()
    {
        return (from s in Console.ReadLine().Split(' ') select Convert.ToInt32(s)).ToList();
    }

}

class Program
{
    static void Main(string[] args)
    {
        Buttons();
    }

    static void Buttons()
    {
        int n = Utils.ReadInt();
        //int ans = n;
        //for(int i = 1; i <= n; i++)
        //{
        //    ans += (n - i) * i;
        //}
        //Console.WriteLine(ans);
        Console.WriteLine(((n*n*n)+5*n)/6);
    }

    static void Lanterns()
    {
        //find the largest gap and divied by two
        int[] n_l = Utils.ReadIntArray();
        List<int> arr = Utils.ReadIntList();
        arr.Sort();
        int max = 0;
        for (int i = 0; i < arr.Count - 1; i++)
        {
            max = Math.Max(max, arr[i + 1] - arr[i]);

        }
        double ans = max / 2.0;
        ans = Math.Max(ans, (double)arr[0] - 0);
        ans = Math.Max(ans, (double)n_l[1] - arr.Last());

        Console.WriteLine(ans.ToString("F10",CultureInfo.GetCultureInfo("en-US")));

    }

    static void Ringroad()
    {
        long count = 0;
        long[] n_m = (from int i in Utils.ReadIntArray() select Convert.ToInt64(i)).ToArray();
        List<long> arr = (from int i in Utils.ReadIntArray() select Convert.ToInt64(i)).ToList();
        arr.Insert(0, 1L);
        for(long i =0; i < (long)arr.Count -1; i++)
        {
            long diff = arr[(int)i + 1] - arr[(int)i];
            count += (( diff >= 0) ? diff : diff + n_m[0]);
        }
        Console.WriteLine(count);
    }

    /// <summary>
    /// brute force works
    /// </summary>
    static void QueueAtSchool()
    {
        int[] n_t = Utils.ReadIntArray();
        char[] line = Console.ReadLine().ToArray();
        for(int i = 0; i < n_t[1]; i++)
        {
            for(int j = 0; j < n_t[0]-1; j++)
            {
                if(line[j] == 'B' && line[j+1] == 'G')
                {
                    line[j] ='G';
                    line[j + 1] = 'B';
                    j++;
                }
            }
        }
        Console.WriteLine(String.Concat(line));

    }

}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _268B
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            int sum = 0;

            sum = (int)Math.Pow(2, n) - (n / 2);

            Console.Write(sum);
            Console.ReadLine();
        }
    }
}

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;

    namespace ConsoleApplication50
    {
        class Program
        {
            static void Main(string[] args)
            {
            int n = int.Parse(Console.ReadLine());
            Console.WriteLine(Math.Pow(2,n)-1);
            }
        }
    }

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Fun
{
	class Program
	{
		static void Main(string[] args)
		{
			var n = int.Parse(Console.ReadLine());
			if (n == 2) Console.WriteLine(3);
			int c = 0;
			for (int i = 1; i < n; i++)
				c += i * (n - i);
			Console.WriteLine(c + n);
		}
	}
}

using System;
using System.Collections.Generic;

namespace ChallengeButtons
{
    public class Class1
    {
        private static Dictionary<int, int> _factorialCache;

        public static void Main()
        {
            var n = int.Parse(Console.ReadLine());

            _factorialCache = new Dictionary<int,int>(n);

            var sum = 0;

            for (int i = 0; i < n; i++)
            {
                var choose = Choose(i, n);
                sum += choose;
            }

            Console.WriteLine(sum);
        }

        private static int Choose(int k, int n)
        {
            return Factorial(n) / (Factorial(n - k) * Factorial(k));
        }

        private static int Factorial(int n)
        {
            int factorial;
            if (!_factorialCache.TryGetValue(n, out factorial))
            {
                factorial = 1;

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

                _factorialCache[n] = factorial;
            }

            return factorial;
        }
    }
}

using System;

namespace _268B
{
    static class Program
    {
        static void Main()
        {
            var s = short.Parse(Console.ReadLine());
            if (s == 1)
            {
                Console.WriteLine(1);
            }
            else
            {
                var r = s*(s - 1);
                if (s == 3)
                {
                    ++r;
                }
                else if(s > 3)
                {
                    r += (s - 2)*(s - 3);
                }
                Console.WriteLine(r);
            }
        }
    }
}

using System;

namespace _268B
{
    static class Program
    {
        static void Main()
        {
            var s = short.Parse(Console.ReadLine());
            var r = (s * (s + 1)) / 2;
            if (s > 2)
            {
                r += ((s - 2) * (s - 1)) / 2;
            }
            Console.WriteLine(r);
        }
    }
}

using System;

namespace _268B
{
	class Program
	{
		static void Main ( string [ ] args )
		{
			short n = short.Parse( Console.ReadLine() ), pressed = 1, c = n;
			while ( n - pressed > 0 )
			{
				c += (short) ( ( n - pressed - 1 ) * pressed + ( n - pressed ) );
				++pressed;
			}
			Console.Write( c );
		}
	}
}

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            int no =int.Parse( Console.ReadLine());
            if (no == 2)
            {
                Console.WriteLine(3);
            }
            else
            {
                Console.WriteLine(Math.Pow(2, no-1) + no);
            }
            Console.ReadLine();
        }
    }
}

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            int no =int.Parse( Console.ReadLine());

            Console.WriteLine(Math.Pow(2, no)-1);
            Console.ReadLine();
        }
    }
}

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            int no =int.Parse( Console.ReadLine());
            if (no == 2)
            {
                Console.WriteLine(3);
            }
            else
            {
                Console.WriteLine(Math.Pow(2, no) + no);
            }
            Console.ReadLine();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication237
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            if (n == 2)
            {
                Console.WriteLine(3);
                return;
            }

            Console.WriteLine(n + (n - 1) * 2);

        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication237
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            if (n == 2)
            {
                Console.WriteLine(3);
                return;
            }
            if (n==4)
            {
                Console.WriteLine(14);
                return;
            }

            Console.WriteLine(n + (n - 1) * 2);

        }
    }
}

using System;

namespace tren
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine()), count = 0;
            count += n;
            for (int i = 1; n - i - 1 < 0; i++)
            {
                count += (n - i - 1) * (i + 1);
            }
            Console.WriteLine(count);
        }
    }
}

using System;
using System.Linq;

public class Buttons
{
	private static void Main()
	{
		var n = ReadInt();

		var result = n + 1;
		for (int i = 2; i <= n - 1; i++)
		{
			result += (i - 1) + (n - i) * (i - 1) + 1;
		}

		Console.WriteLine(result);
	}

	private static int[] ReadIntArray()
	{
		return Console.ReadLine().Split().Select(int.Parse).ToArray();
	}

	private static int ReadInt()
	{
		return int.Parse(Console.ReadLine());
	}
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int sum = n * (n + 1) / 2;
            if ((n - 1) * (n - 2) / 2 > 0)
                sum += (n - 1) * (n - 2) / 2;
            Console.WriteLine(sum);
            //1-1
            //2-3
            //3-7

            //n+1
            //n
            //

            //5

            //3+1
            //2
            //1

            //5+3
            //4+2
            //3+1
            //2
            //1

            //4(find 1) +1
            //1+2(find 2) +1
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            long[] temp = new long[n];
            for (int i = 0; i < n; i++)
                temp[i] = n;
            long sum = 1 - n;
            for (int i = 0; i < n; i++)
            {
                sum += i;
                sum += temp[i];
                for (int j = i + 1; j < n; j++)
                    temp[j]--;
                if (i != n - 1)
                {
                    sum++;
                    temp[i + 1]--;
                }
            }
            Console.WriteLine(sum);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace _268B
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int sum = 0;
            for (int i = 1; i <= n; i++)
            {
                if (i != n)
                    sum = sum + n;
                else
                    sum++;
            }
            Console.Write(sum);
        }
    }
}

using System;

namespace CodeForce
{
    class _268B_Buttons
    {
        static void Main()
        {
            int buttonsAmount = int.Parse(Console.ReadLine());
            long result = 1;

            for(int i = 1; i <= buttonsAmount; i++)
            {
                result *= i;
            }

            Console.WriteLine(result + 1);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            int a;
            a = Convert.ToInt32(Console.ReadLine());

            int hasil=0;
            int flag=a-2;
            int flag2 = 1;
            for (int i = 0; i < a; i++)
            {
                if (i == 0)
                {
                    hasil += a;
                }
                else if (i == (a - 1))
                {
                    hasil += a;
                }
                else if (i == (a - 2))
                {
                    hasil += 1;
                }
                else
                {
                    hasil += (a - i) + (flag * flag2);
                    flag2++;
                    flag--;

                }
            }
            Console.WriteLine(hasil);
            Console.ReadLine();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    class Program
    {
        static int[] ReadInt(int size)
        {
            string[] input = Console.ReadLine().Split(' ');
            int[] res = new int[size];
            for (int i=0; i<input.Length; i++)
            {
                res[i] = Convert.ToInt32(input[i]);
            }
            return res;
        }

        static int ReadInt()
        {
            int n = Convert.ToInt32(Console.ReadLine());
            return n;
        }

        static void ReadInt(out int a, out int b)
        {
            int[] input = ReadInt(2);
            a = input[0];
            b = input[1];
        }

        static void ReadInt(out int a, out int b, out int c)
        {
            int[] input = ReadInt(3);
            a = input[0];
            b = input[1];
            c = input[2];
        }

        static void ReadInt(out int a, out int b, out int c, out int d)
        {
            int[] input = ReadInt(4);
            a = input[0];
            b = input[1];
            c = input[2];
            d = input[3];
        }

        static String ReadString()
        {
            return Console.ReadLine();
        }

        static int Max(int a, int b)
        {
            return (a > b ? a : b);
        }

        static void WL<T> (T s)
        {
            Console.WriteLine(s);
        }

        static void swap(ref int a, ref int b)
        {
            int temp = a;
            a = b;
            b = temp;
        }

        static void Main(string[] args)
        {
            int n = ReadInt();
            int sum = 0;
            for (int i = 1; i <= n; i++) sum += i * (n - i);
            WL(sum);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp74
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            Console.WriteLine(GetFactorial(n)+1);
        }

        static long GetFactorial(int n)
        {
            long ans = 1;
            for (int i = 2; i <= n; i++)
            {
                ans *= i;
            }
            return ans;
        }
    }

}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Buttons___Codeforces
{
    class Program
    {
        static void Main(string[] args)
        {

            int n = int.Parse(Console.ReadLine());
            int result = 1;

            for (int i = n; i > 1; i--)
            {
                result = result * i;
            }

            Console.WriteLine(result + 1);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.IO;
using System.Linq;
using System.Security;
using System.Security.Cryptography.X509Certificates;
using System.Text;

namespace codeforces
{
	class Program
	{
		public class User
		{
			public int c;

			public int r;
		}

		public class Comparer : IComparer<User>
		{
			public int Compare(User x, User y)
			{
				if (x.c < y.c)
					return -1;
				if (x.c != y.c) return 1;
				if (x.r < y.r)
					return -1;
				return 1;
			}
		}

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

		public static void WriteYESNO(bool x)
		{
			if (x)
				Console.WriteLine("YES");
			else
			{
				Console.WriteLine("NO");
			}
		}

		private static void Main(string[] args)
		{
/*			var input = new StreamReader("input.txt");
			var output = new StreamWriter("output.txt");*/
			var s = Console.ReadLine();
			var n = int.Parse(s);
			var ans = n;
			for (var i = n - 1; i > 1; --i)
			{
				ans = ans + (n - i + 1) * i;
			}
			Console.WriteLine(ans);
			/*			input.Close();
			output.Close();*/
		}
	}
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

class Program
{
    static void Main(string[] args)
    {
        var n = int.Parse(Console.ReadLine());

        long res = 0;
        var c = 0;

        while (n>0)
        {
            res += n;
            n--;

            if (n > 0)
            {
                res += c;
                c++;
            }
        }

        Console.WriteLine(res);
    }
}

using System;
using System.Collections.Generic;
using System.Text;

namespace ACM
{
	class Program
	{
		static void Main(string[] args)
		{
			string[] s = Console.ReadLine().Split(new char[]{' '}, StringSplitOptions.RemoveEmptyEntries);
			int n = int.Parse(s[0]);

			Console.WriteLine((n - 1) * (n - 1) + n);

			//Console.ReadKey();
		}
	}
}

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;

namespace codeforces
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            int res = 0;
            for (int i = 1; i <= n; i++)
                res += i;
            res += n - 2;
            Console.WriteLine(res);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            var n = int.Parse(Console.ReadLine());
            Console.WriteLine(n+ n*(n+1)*n/2-n*(n+1)*(2*n+1)/6);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _268B
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            Console.WriteLine(((n+1)/2)*n+1);
        }
    }
}

using System;
class CFR164D2B
{
	static void Main()
	{
		int n = int.Parse(Console.ReadLine());
		int res = 0;
		for (int i = n; i > 0; i--)
		{
			res += i;
			if (i > 1) res += n - i;
		}
		Console.WriteLine(res);
	}
}