#include <bits/stdc++.h>
using namespace std;
typedef long long int64;
typedef complex<long double> cmplx;
const long double pi = 3.14159265358979323846;
const int inf = (int)2e+9 + 2;
const int mod = 998244353;
const long double eps = 1e-8;
const int N = 100'000;

int n, m, k1, k2;
vector<int> g[1000];
int in[1000];
int p[1000];
int out[1000];
int timer = 0;
set<int> st1;
set<int> st2;

bool upper(int i, int j)
{
  return in[i] < in[j] && out[j] < out[i];
}

void dfs(int v)
{
  in[v] = timer++;
  for (auto to : g[v]) {
    if (to != p[v]) {
      p[to] = v;
      dfs(to);
    }
  }
  out[v] = timer++;
}

int ask(int val, char type)
{
  cout << type << ' ' << val + 1 << endl;
  int res;
  cin >> res;
  --res;
  return res;
}

void solve()
{
  cin >> n;
  for (int i = 0; i < n - 1; ++i) {
    int x, y;
    cin >> x >> y;
    --x; --y;
    g[x].push_back(y);
    g[y].push_back(x);
  }
  dfs(0);
  cin >> k1;
  for (int i = 0; i < k1; ++i) {
    int x; cin >> x; --x;
    st1.insert(x);
  }
  cin >> k2;
  for (int i = 0; i < k2; ++i) {
    int x; cin >> x; --x;
    st2.insert(x);
  }
  int v = ask(*st2.begin(), 'B');
  if (st1.find(v) != st1.end())
    cout << "C " << v + 1 << endl;
  else {
    int my = *st1.begin();
    if (upper(my, v)) {
      my = v;
      while (st1.find(my) == st1.end())
        my = p[my];
      v = ask(my, 'A');
      if (st2.find(v) == st2.end())
        cout << "C -1" << endl;
      else
        cout << "C " << my + 1 << endl;
    }
    else {
      if (upper(v, my)) {
        while (my && st1.find(p[my]) != st1.end())
          my = p[my];
        v = ask(my, 'A');
        if (st2.find(v) == st2.end())
          cout << "C -1" << endl;
        else
          cout << "C " << my + 1 << endl;
      }
      else {
        while (!upper(my, v) && st1.find(p[my]) != st1.end())
          my = p[my];
        v = ask(my, 'A');
        if (st2.find(v) == st2.end())
          cout << "C -1" << endl;
        else
          cout << "C " << my + 1 << endl;
      }
    }
  }
  st1.clear();
  st2.clear();
  timer = 0;
  for (int i = 0; i < n; ++i)
    g[i].clear();
  memset(p, 0, sizeof(p));
}

void precalc()
{
}

int main()
{
  ios::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  precalc();
  int test = 1;
  cin >> test;
  for (; test; --test)
      solve();
  return 0;
}


#include <bits/stdc++.h>
using namespace std;
typedef long long int64;
typedef complex<long double> cmplx;
const long double pi = 3.14159265358979323846;
const int inf = (int)2e+9 + 2;
const int mod = 998244353;
const long double eps = 1e-8;
const int N = 100'000;

int n, m, k1, k2;
vector<int> g[1000];
int a[1000];
int b[1000];
int was[1000];
int q[1000];

int ask(int val, char type)
{
  cout << type << ' ' << val + 1 << endl;
  int res;
  cin >> res;
  --res;
  return res;
}

void solve(int test)
{
  cin >> n;
  for (int i = 0; i < n - 1; ++i) {
    int x, y;
    cin >> x >> y;
    --x; --y;
    g[x].push_back(y);
    g[y].push_back(x);
  }
  cin >> k1;
  for (int i = 0; i < k1; ++i) {
    int x; cin >> x; --x;
    a[x] = test;
  }
  cin >> k2;
  int v;
  for (int i = 0; i < k2; ++i)  {
    int x; cin >> x; --x;
    b[x] = test;
    v = x;
  }
  int qb = 0, qe = 1;
  v = ask(v, 'B');
  q[0] = v;
  was[v] = test;
  while (a[v] != test) {
    v = q[qb++];
    for (auto to : g[v]) {
      if (was[to] != test) {
        was[to] = test;
        q[qe++] = to;
      }
    }
  }
  if (b[ask(v, 'A')] == test)
    cout << "C " <<  v + 1 << endl;
  else
    cout << "C -1" << endl;
  for (int i = 0; i < n; ++i)
    g[i].clear();
}

void precalc()
{
}

int main()
{
  ios::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  precalc();
  int test = 1;
  cin >> test;
  for (int i = 1; i <= test; ++i)
      solve(test);
  return 0;
}


#include <bits/stdc++.h>
using namespace std;
typedef long long int64;
typedef complex<long double> cmplx;
const long double pi = 3.14159265358979323846;
const int inf = (int)2e+9 + 2;
const int mod = 998244353;
const long double eps = 1e-8;
const int N = 100'000;

int n, m, k1, k2;
vector<int> g[1000];
int a[1000];
int b[1000];
int was[1000];
int q[1000];

int ask(int val, char type)
{
  cout << type << ' ' << val + 1 << endl;
  int res;
  cin >> res;
  --res;
  return res;
}

void solve(int test)
{
  cin >> n;
  for (int i = 0; i < n - 1; ++i) {
    int x, y;
    cin >> x >> y;
    --x; --y;
    g[x].push_back(y);
    g[y].push_back(x);
  }
  cin >> k1;
  for (int i = 0; i < k1; ++i) {
    int x; cin >> x; --x;
    a[x] = test;
  }
  cin >> k2;
  int v;
  for (int i = 0; i < k2; ++i)  {
    int x; cin >> x; --x;
    b[x] = test;
    v = x;
  }
  int qb = 0, qe = 1;
  v = ask(v, 'B');
  q[0] = v;
  was[v] = test;
  while (a[v] != test) {
    v = q[qb++];
    for (auto to : g[v]) {
      if (was[to] != test) {
        was[to] = test;
        q[qe++] = to;
      }
    }
  }
  if (b[ask(v, 'A')] == test)
    cout << "C " <<  v + 1 << endl;
  else
    cout << "C -1" << endl;
  for (int i = 0; i < n; ++i)
    g[i].clear();
}

void precalc()
{
}

int main()
{
  ios::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  precalc();
  int test = 1;
  cin >> test;
  for (int i = 1; i <= test; ++i)
      solve(i);
  return 0;
}


#include <bits/stdc++.h>
using namespace std;
typedef long long int64;
typedef complex<long double> cmplx;
const long double pi = 3.14159265358979323846;
const int inf = (int)2e+9 + 2;
const int mod = 998244353;
const long double eps = 1e-8;
const int N = 100'000;

int n, m, k1, k2;
vector<int> g[1000];
int in[1000];
int p[1000];
int out[1000];
int timer = 0;
set<int> st1;
set<int> st2;

bool upper(int i, int j)
{
  return in[i] < in[j] && out[j] < out[i];
}

void dfs(int v)
{
  in[v] = timer++;
  for (auto to : g[v]) {
    if (to != p[v]) {
      p[to] = v;
      dfs(to);
    }
  }
  out[v] = timer++;
}

int ask(int val, char type)
{
  cout << type << ' ' << val + 1 << endl;
  int res;
  cin >> res;
  --res;
  return res;
}

void solve()
{
  cin >> n;
  for (int i = 0; i < n - 1; ++i) {
    int x, y;
    cin >> x >> y;
    --x; --y;
    g[x].push_back(y);
    g[y].push_back(x);
  }
  dfs(0);
  cin >> k1;
  for (int i = 0; i < k1; ++i) {
    int x; cin >> x; --x;
    st1.insert(x);
  }
  cin >> k2;
  for (int i = 0; i < k2; ++i) {
    int x; cin >> x; --x;
    st2.insert(x);
  }
  int v = ask(*st2.begin(), 'B');
  if (st1.find(v) != st1.end())
    cout << "C " << v + 1 << endl;
  else {
    int my = *st1.begin();
    if (upper(my, v)) {
      while (st1.find(v) == st1.end())
        v = p[v];
      my = ask(v, 'A');
      if (st2.find(my) == st2.end())
        cout << "C -1" << endl;
      else
        cout << "C " << v + 1 << endl;
    }
    else {
      while (!upper(v, my) && st1.find(v) == st1.end())
        v = p[v];
      my = ask(v, 'A');
      if (st1.find(v) == st1.end() || st2.find(my) == st2.end())
        cout << "C -1" << endl;
      else
        cout << "C " << v + 1 << endl;
    }
  }
  st1.clear();
  st2.clear();
  timer = 0;
  for (int i = 0; i < n; ++i)
    g[i].clear();
  memset(p, 0, sizeof(p));
}

void precalc()
{
}

int main()
{
  ios::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  precalc();
  int test = 1;
  cin >> test;
  for (; test; --test)
      solve();
  return 0;
}


#include <bits/stdc++.h>
using namespace std;
typedef long long int64;
typedef complex<long double> cmplx;
const long double pi = 3.14159265358979323846;
const int inf = (int)2e+9 + 2;
const int mod = 998244353;
const long double eps = 1e-8;
const int N = 100'000;

int n, m, k1, k2;
vector<int> g[1000];
int in[1000];
int p[1000];
int out[1000];
int h[1000];
int timer = 0;
set<int> st1;
set<int> st2;

bool upper(int i, int j)
{
  return in[i] < in[j] && out[j] < out[i];
}

void dfs(int v, int val)
{
  in[v] = timer++;
  h[v] = val;
  for (auto to : g[v]) {
    if (to != p[v]) {
      p[to] = v;
      dfs(to, val + 1);
    }
  }
  out[v] = timer++;
}

int ask(int val, char type)
{
  cout << type << ' ' << val + 1 << endl;
  int res;
  cin >> res;
  --res;
  return res;
}

void solve()
{
  cin >> n;
  for (int i = 0; i < n - 1; ++i) {
    int x, y;
    cin >> x >> y;
    --x; --y;
    g[x].push_back(y);
    g[y].push_back(x);
  }
  dfs(0, 0);
  cin >> k1;
  for (int i = 0; i < k1; ++i) {
    int x; cin >> x; --x;
    st1.insert(x);
  }
  cin >> k2;
  for (int i = 0; i < k2; ++i) {
    int x; cin >> x; --x;
    st2.insert(x);
  }
  int v = ask(*st2.begin(), 'B');
  if (st1.find(v) != st1.end())
    cout << "C " << v + 1 << endl;
  else {
    int my = *st1.begin();
    if (upper(my, v)) {
      my = v;
      while (st1.find(my) == st1.end())
        my = p[my];
      v = ask(my, 'A');
      if (st2.find(v) == st2.end())
        cout << "C -1" << endl;
      else
        cout << "C " << v << endl;
    }
    else {
      while (st1.find(p[my]) != st1.end())
        my = p[my];
      v = ask(my, 'A');
      if (st2.find(v) == st2.end())
        cout << "C -1" << endl;
      else
        cout << "C " << v << endl;

    }
  }
  st1.clear();
  st2.clear();
  timer = 0;
  for (int i = 0; i < n; ++i)
    g[i].clear();
  memset(p, 0, sizeof(int) * n);
}

void precalc()
{
}

int main()
{
  ios::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  precalc();
  int test = 1;
  cin >> test;
  for (; test; --test)
      solve();
  return 0;
}


#include <bits/stdc++.h>
using namespace std;
typedef long long int64;
typedef complex<long double> cmplx;
const long double pi = 3.14159265358979323846;
const int inf = (int)2e+9 + 2;
const int mod = 998244353;
const long double eps = 1e-8;
const int N = 100'000;

int n, m, k1, k2;
vector<int> g[1000];
int in[1000];
int p[1000];
int out[1000];
int timer = 0;
set<int> st1;
set<int> st2;

bool upper(int i, int j)
{
  return in[i] < in[j] && out[j] < out[i];
}

void dfs(int v)
{
  in[v] = timer++;
  for (auto to : g[v]) {
    if (to != p[v]) {
      p[to] = v;
      dfs(to);
    }
  }
  out[v] = timer++;
}

int ask(int val, char type)
{
  cout << type << ' ' << val + 1 << endl;
  int res;
  cin >> res;
  --res;
  return res;
}

void solve()
{
  cin >> n;
  for (int i = 0; i < n - 1; ++i) {
    int x, y;
    cin >> x >> y;
    --x; --y;
    g[x].push_back(y);
    g[y].push_back(x);
  }
  dfs(0);
  cin >> k1;
  for (int i = 0; i < k1; ++i) {
    int x; cin >> x; --x;
    st1.insert(x);
  }
  cin >> k2;
  for (int i = 0; i < k2; ++i) {
    int x; cin >> x; --x;
    st2.insert(x);
  }
  int v = ask(*st2.begin(), 'B');
  if (st1.find(v) != st1.end())
    cout << "C " << v + 1 << endl;
  else {
    int my = *st1.begin();
    if (upper(my, v)) {
      my = v;
      while (st1.find(my) == st1.end())
        my = p[my];
      v = ask(my, 'A');
      if (st2.find(v) == st2.end())
        cout << "C -1" << endl;
      else
        cout << "C " << v + 1 << endl;
    }
    else {
      if (upper(v, my) {
        while (my && st1.find(p[my]) != st1.end())
          my = p[my];
        v = ask(my, 'A');
        if (st2.find(v) == st2.end())
          cout << "C -1" << endl;
        else
          cout << "C " << v + 1 << endl;
      }
      else {
        while (!upper(my, v) && st1.find(p[my]) != st1.end())
          my = p[my];
        v = ask(my, 'A');
        if (st2.find(v) == st2.end())
          cout << "C -1" << endl;
        else
          cout << "C " << v + 1 << endl;
      }
    }
  }
  st1.clear();
  st2.clear();
  timer = 0;
  for (int i = 0; i < n; ++i)
    g[i].clear();
  memset(p, 0, sizeof(p));
}

void precalc()
{
}

int main()
{
  ios::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  precalc();
  int test = 1;
  cin >> test;
  for (; test; --test)
      solve();
  return 0;
}


#include <bits/stdc++.h>
using namespace std;
typedef long long int64;
typedef complex<long double> cmplx;
const long double pi = 3.14159265358979323846;
const int inf = (int)2e+9 + 2;
const int mod = 998244353;
const long double eps = 1e-8;
const int N = 100'000;

int n, m, k1, k2;
vector<int> g[1000];
int a[1000];
int b[1000];
int was[1000];
int q[1000];

int ask(int val, char type)
{
  cout << type << ' ' << val + 1 << endl;
  int res;
  cin >> res;
  --res;
  return res;
}

void solve(int test)
{
  cin >> n;
  for (int i = 0; i < n - 1; ++i) {
    int x, y;
    cin >> x >> y;
    --x; --y;
    g[x].push_back(y);
    g[y].push_back(x);
  }
  cin >> k1;
  for (int i = 0; i < k1; ++i) {
    int x; cin >> x; --x;
    a[x] = test;
  }
  cin >> k2;
  for (int i = 0; i < k2; ++i)  {
    int x; cin >> x; --x;
    b[x] = test;
  }
  int qb = 0, qe = 1;
  q[0] = ask(b[0], 'B');
  was[q[0]] = test;
  for (;;) {
    int v = q[qb++];
    for (auto to : g[v]) {
      if (a[to] == test) {
        qb = to;
        goto out;
      }
      if (was[to] != test) {
        was[to] = test;
        q[qe++] = to;
      }
    }
  }
out:
  qb = ask(qb, 'A');
  if (b[qb] == test)
    cout << qb + 1 << endl;
  else
    cout << "C -1" << endl;
  for (int i = 0; i < n; ++i)
    g[i].clear();
}

void precalc()
{
}

int main()
{
  ios::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  precalc();
  int test = 1;
  cin >> test;
  for (int i = 1; i <= test; ++test)
      solve(test);
  return 0;
}


#include <bits/stdc++.h>
using namespace std;
typedef long long int64;
typedef complex<long double> cmplx;
const long double pi = 3.14159265358979323846;
const int inf = (int)2e+9 + 2;
const int mod = 998244353;
const long double eps = 1e-8;
const int N = 100'000;

int n, m, k1, k2;
vector<int> g[1000];
int a[1000];
int b[1000];
int was[1000];
int q[1000];

int ask(int val, char type)
{
  cout << type << ' ' << val + 1 << endl;
  int res;
  cin >> res;
  --res;
  return res;
}

void solve(int test)
{
  cin >> n;
  for (int i = 0; i < n - 1; ++i) {
    int x, y;
    cin >> x >> y;
    --x; --y;
    g[x].push_back(y);
    g[y].push_back(x);
  }
  cin >> k1;
  for (int i = 0; i < k1; ++i) {
    int x; cin >> x; --x;
    a[x] = test;
  }
  cin >> k2;
  int v;
  for (int i = 0; i < k2; ++i)  {
    int x; cin >> x; --x;
    b[x] = test;
    v = x;
  }
  int qb = 0, qe = 1;
  q[0] = ask(v, 'B');
  was[v] = test;
  while (a[v] != test) {
    v = q[qb++];
    for (auto to : g[v]) {
      if (was[to] != test) {
        was[to] = test;
        q[qe++] = to;
      }
    }
  }
  if (b[ask(v, 'A')] == test)
    cout << v + 1 << endl;
  else
    cout << "C -1" << endl;
  for (int i = 0; i < n; ++i)
    g[i].clear();
}

void precalc()
{
}

int main()
{
  ios::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  precalc();
  int test = 1;
  cin >> test;
  for (int i = 1; i <= test; ++i)
      solve(test);
  return 0;
}


//ALEX ENACHE

#include <vector>
#include <algorithm>
#include <queue>
#include <map>
#include <set>
#include <unordered_map>
#include <time.h>
#include <iomanip>
#include <deque>
#include <math.h>
#include <cmath>
#include <assert.h>
#include <stack>
#include <bitset>
#include <random>
#include <chrono>

using namespace std;

#include <iostream>

//#include <fstream>
//ifstream cin ("input");ofstream cout ("output");

int f1[1010];
int f2[1010];
int used[1010];

queue <int> q;

vector <int> gr[1010];

int main() {

    //freopen("input" , "r" , stdin);freopen("output" , "w" , stdout);

    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    int t;
    cin>>t;

    while (t--){
        int n;
        cin>>n;

        for (int i=1; i<n; i++){
            int a , b;
            cin>>a>>b;
            gr[a].push_back(b);
            gr[b].push_back(a);
        }

        int k1 , k2;
        cin>>k1;
        int nr;
        for (int i=1; i<=k1; i++){
            cin>>nr;
            f1[nr] = 1;
        }
        cin>>k2;
        for (int i=1; i<=k2; i++){
            cin>>nr;
            f2[nr] = 1;
        }

        cout<<"B "<<nr<<endl;
        cin>>nr;
        used[nr] = 1;
        q.push(nr);

        int ok = 0;

        while (!q.empty()){
            int now = q.front();
            q.pop();
            if (f1[now]){
                cout<<"A "<<now<<endl;
                cin>>nr;
                if (f2[nr]){
                    ok = now;
                }
                break;
            }
            for (auto &x : gr[now]){
                if (!used[x]){
                    used[x] = 1;
                    q.push(x);
                }
            }
        }

        if (!ok){
            cout<<"C -1";
        }
        else{
            cout<<"C "<<ok<<endl;
        }

        for (int i=1; i<=n; i++) {
            gr[i].clear();
            used[i] = 0;
            f1[i] = 0;
            f2[i] = 0;
        }

    }

    return 0;
}


//ALEX ENACHE

#include <vector>
#include <algorithm>
#include <queue>
#include <map>
#include <set>
#include <unordered_map>
#include <time.h>
#include <iomanip>
#include <deque>
#include <math.h>
#include <cmath>
#include <assert.h>
#include <stack>
#include <bitset>
#include <random>
#include <chrono>

using namespace std;

#include <iostream>

//#include <fstream>
//ifstream cin ("input");ofstream cout ("output");

int f1[1010];
int f2[1010];
int used[1010];

queue <int> q;

vector <int> gr[1010];

int main() {

    //freopen("input" , "r" , stdin);freopen("output" , "w" , stdout);

    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    int t;
    cin>>t;

    while (t--){
        int n;
        cin>>n;

        for (int i=1; i<n; i++){
            int a , b;
            cin>>a>>b;
            gr[a].push_back(b);
            gr[b].push_back(a);
        }

        int k1 , k2;
        cin>>k1;
        int nr;
        for (int i=1; i<=k1; i++){
            cin>>nr;
            f1[i] = 1;
        }
        cin>>k2;
        for (int i=1; i<=k1; i++){
            cin>>nr;
            f2[i] = 1;
        }

        cout<<"B "<<nr<<endl;
        cin>>nr;
        used[nr] = 1;
        q.push(nr);

        int ok = 0;

        while (!q.empty()){
            int now = q.front();
            q.pop();
            if (f1[now]){
                cout<<"A "<<now<<endl;
                cin>>nr;
                if (f2[nr]){
                    ok = nr;
                }
                break;
            }
            for (auto &x : gr[now]){
                if (!used[x]){
                    used[x] = 1;
                    q.push(x);
                }
            }
        }

        if (!ok){
            cout<<-1;
        }
        else{
            cout<<"C "<<ok<<endl;
        }

        for (int i=1; i<=n; i++) {
            gr[i].clear();
            used[i] = 0;
            f1[i] = 0;
            f2[i] = 0;
        }

    }

    return 0;
}


//ALEX ENACHE

#include <vector>
#include <algorithm>
#include <queue>
#include <map>
#include <set>
#include <unordered_map>
#include <time.h>
#include <iomanip>
#include <deque>
#include <math.h>
#include <cmath>
#include <assert.h>
#include <stack>
#include <bitset>
#include <random>
#include <chrono>

using namespace std;

#include <iostream>

//#include <fstream>
//ifstream cin ("input");ofstream cout ("output");

int f1[1010];
int f2[1010];
int used[1010];

queue <int> q;

vector <int> gr[1010];

int main() {

    //freopen("input" , "r" , stdin);freopen("output" , "w" , stdout);

    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    int t;
    cin>>t;

    while (t--){
        int n;
        cin>>n;

        for (int i=1; i<n; i++){
            int a , b;
            cin>>a>>b;
            gr[a].push_back(b);
            gr[b].push_back(a);
        }

        int k1 , k2;
        cin>>k1;
        int nr;
        for (int i=1; i<=k1; i++){
            cin>>nr;
            f1[nr] = 1;
        }
        cin>>k2;
        for (int i=1; i<=k2; i++){
            cin>>nr;
            f2[nr] = 1;
        }

        cout<<"B "<<nr<<endl;
        cin>>nr;
        used[nr] = 1;
        q.push(nr);

        int ok = 0;

        while (!q.empty()){
            int now = q.front();
            q.pop();
            if (f1[now]){
                cout<<"A "<<now<<endl;
                cin>>nr;
                if (f2[nr]){
                    ok = now;
                }
                break;
            }
            for (auto &x : gr[now]){
                if (!used[x]){
                    used[x] = 1;
                    q.push(x);
                }
            }
        }

        if (!ok){
            cout<<"C -1"<<endl;
        }
        else{
            cout<<"C "<<ok<<endl;
        }

        for (int i=1; i<=n; i++) {
            gr[i].clear();
            used[i] = 0;
            f1[i] = 0;
            f2[i] = 0;
        }
        while (!q.empty()){
            q.pop();
        }

    }

    return 0;
}


//ALEX ENACHE

#include <vector>
#include <algorithm>
#include <queue>
#include <map>
#include <set>
#include <unordered_map>
#include <time.h>
#include <iomanip>
#include <deque>
#include <math.h>
#include <cmath>
#include <assert.h>
#include <stack>
#include <bitset>
#include <random>
#include <chrono>

using namespace std;

#include <iostream>

//#include <fstream>
//ifstream cin ("input");ofstream cout ("output");

int f1[1010];
int f2[1010];
int used[1010];

queue <int> q;

vector <int> gr[1010];

int main() {

    //freopen("input" , "r" , stdin);freopen("output" , "w" , stdout);

    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    int t;
    cin>>t;

    while (t--){
        int n;
        cin>>n;

        for (int i=1; i<n; i++){
            int a , b;
            cin>>a>>b;
            gr[a].push_back(b);
            gr[b].push_back(a);
        }

        int k1 , k2;
        cin>>k1;
        int nr;
        for (int i=1; i<=k1; i++){
            cin>>nr;
            f1[nr] = 1;
        }
        cin>>k2;
        for (int i=1; i<=k2; i++){
            cin>>nr;
            f2[nr] = 1;
        }

        cout<<"B "<<nr<<endl;
        cin>>nr;
        used[nr] = 1;
        q.push(nr);

        int ok = 0;

        while (!q.empty()){
            int now = q.front();
            q.pop();
            if (f1[now]){
                cout<<"A "<<now<<endl;
                cin>>nr;
                if (f2[nr]){
                    ok = now;
                }
                break;
            }
            for (auto &x : gr[now]){
                if (!used[x]){
                    used[x] = 1;
                    q.push(x);
                }
            }
        }

        if (!ok){
            cout<<"C -1";
        }
        else{
            cout<<"C "<<ok<<endl;
        }

        for (int i=1; i<=n; i++) {
            gr[i].clear();
            used[i] = 0;
            f1[i] = 0;
            f2[i] = 0;
        }
        while (!q.empty()){
            q.pop();
        }

    }

    return 0;
}


//ALEX ENACHE

#include <vector>
#include <algorithm>
#include <queue>
#include <map>
#include <set>
#include <unordered_map>
#include <time.h>
#include <iomanip>
#include <deque>
#include <math.h>
#include <cmath>
#include <assert.h>
#include <stack>
#include <bitset>
#include <random>
#include <chrono>

using namespace std;

#include <iostream>

//#include <fstream>
//ifstream cin ("input");ofstream cout ("output");

int f1[1010];
int f2[1010];
int used[1010];

queue <int> q;

vector <int> gr[1010];

int main() {

    //freopen("input" , "r" , stdin);freopen("output" , "w" , stdout);

    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    int t;
    cin>>t;

    while (t--){
        int n;
        cin>>n;

        for (int i=1; i<n; i++){
            int a , b;
            cin>>a>>b;
            gr[a].push_back(b);
            gr[b].push_back(a);
        }

        int k1 , k2;
        cin>>k1;
        int nr;
        for (int i=1; i<=k1; i++){
            cin>>nr;
            f1[nr] = 1;
        }
        cin>>k2;
        for (int i=1; i<=k2; i++){
            cin>>nr;
            f2[nr] = 1;
        }

        cout<<"B "<<nr<<endl;
        cin>>nr;
        used[nr] = 1;
        q.push(nr);

        int ok = 0;

        while (!q.empty()){
            int now = q.front();
            q.pop();
            if (f1[now]){
                cout<<"A "<<now<<endl;
                cin>>nr;
                if (f2[nr]){
                    ok = nr;
                }
                break;
            }
            for (auto &x : gr[now]){
                if (!used[x]){
                    used[x] = 1;
                    q.push(x);
                }
            }
        }

        if (!ok){
            cout<<"C -1";
        }
        else{
            cout<<"C "<<ok<<endl;
        }

        for (int i=1; i<=n; i++) {
            gr[i].clear();
            used[i] = 0;
            f1[i] = 0;
            f2[i] = 0;
        }

    }

    return 0;
}


#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef pair<int, int> pi;
#define debug(x) cerr << #x << ": " << x << endl;
#define debug2(x, y) debug(x) debug(y);
#define repn(i, a, b) for(int i = (int)(a); i < (int)(b); i++)
#define rep(i, a) for(int i = 0; i < (int)(a); i++)
#define all(v) v.begin(), v.end()
#define mp make_pair
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define fi first
#define se second
#define sq(x) ((x) * (x))

template<class T> T gcd(T a, T b){ return ((b == 0) ? a : gcd(b, a % b)); }

int query(char c, int nd){
	cout << c << " " << nd + 1 << endl;
	int ret;
	cin >> ret;
	return (ret - 1);
}

int ans;
int vs[1005], vs1[1005];
vi g[1005];

void dfs(int cur, int prev){
	if(vs[cur]){
		//check if this is also a yellow
		int q = query('A', cur);
		if(vs1[q]) ans = cur + 1;
		return; //we don't continue from it
	}
	for(int x : g[cur]) if(x != prev) dfs(x, cur);
}

void solve(){
	int n;
	cin >> n;
	ans = -1;
	rep(i, n) g[i].clear();
	rep(i, n - 1){
		int a, b;
		cin >> a >> b;
		a--, b--;
		g[a].pb(b);
		g[b].pb(a);
	}
	int k1;
	cin >> k1;
	vi x(k1);
	memset(vs, 0, sizeof(vs));
	memset(vs1, 0, sizeof(vs1));
	rep(i, k1) cin >> x[i], x[i]--, vs[x[i]] = 1;
	int k2;
	cin >> k2;
	vi y(k2);
	rep(i, k2) cin >> y[i], y[i]--, vs1[y[i]] = 1;
	int q = query('B', y[0]);
	if(vs[q]){ //the node we asked happens to be a green
		cout << "C " << q + 1 << endl;
		return;
	}
	dfs(q, -1);
	cout << "C -1" << endl;
}

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	//freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
	int t;
	cin >> t;
	while(t--) solve();
	return 0;
}
/*
Things to look out for:
	- Integer overflows
	- Array bounds
	- Special cases
Be careful!
*/


#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef pair<int, int> pi;
#define debug(x) cerr << #x << ": " << x << endl;
#define debug2(x, y) debug(x) debug(y);
#define repn(i, a, b) for(int i = (int)(a); i < (int)(b); i++)
#define rep(i, a) for(int i = 0; i < (int)(a); i++)
#define all(v) v.begin(), v.end()
#define mp make_pair
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define fi first
#define se second
#define sq(x) ((x) * (x))

template<class T> T gcd(T a, T b){ return ((b == 0) ? a : gcd(b, a % b)); }

int query(char c, int nd){
	cout << c << " " << nd + 1 << endl;
	int ret;
	cin >> ret;
	return (ret - 1);
}

int ans;
int vs[1005], vs1[1005];
vi g[1005];

void dfs(int cur, int prev){
	if(vs[cur]){
		//check if this is also a yellow
		int q = query('A', cur);
		if(vs1[q]) ans = cur + 1;
		return; //we don't continue from it
	}
	for(int x : g[cur]) if(x != prev) dfs(x, cur);
}

void solve(){
	int n;
	cin >> n;
	ans = -1;
	rep(i, n) g[i].clear();
	rep(i, n - 1){
		int a, b;
		cin >> a >> b;
		a--, b--;
		g[a].pb(b);
		g[b].pb(a);
	}
	int k1;
	cin >> k1;
	vi x(k1);
	memset(vs, 0, sizeof(vs));
	memset(vs1, 0, sizeof(vs1));
	rep(i, k1) cin >> x[i], x[i]--, vs[x[i]] = 1;
	int k2;
	cin >> k2;
	vi y(k2);
	rep(i, k2) cin >> y[i], y[i]--, vs1[y[i]] = 1;
	int q = query('B', y[0]);
	if(vs[q]){ //the node we asked happens to be a green
		cout << "C " << q + 1 << endl;
		return;
	}
	dfs(q, -1);
	cout << "C " << ans << endl;
}

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	//freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
	int t;
	cin >> t;
	while(t--) solve();
	return 0;
}
/*
Things to look out for:
	- Integer overflows
	- Array bounds
	- Special cases
Be careful!
*/


//STARTCOPY
#include<bits/stdc++.h>
using namespace std;

using u_counter_type = unsigned int;
using need_int = int;
using counter_type = int;
using MAIN = int;
#define int DontUseIntÉ
using ll = long long;

template<typename T>
using PairOf = pair<T,T>;

using Void = tuple<>;

struct BasicInitialization{
    BasicInitialization(){
        ios_base::sync_with_stdio(false);
    }
};
BasicInitialization __basic_initialization__;
namespace mytl{

template<typename T, typename R>
vector<R> fmap(R(*f)(const T), const vector<T>& t){
    vector<R> res;
    for(auto elem : t) res.push_back(f(elem));
    return res;
}

template<typename T>
vector<T> forrange(T n, T from){
    vector<T> res(n);
    iota(res.begin(), res.end(), from);
    return res;
}

template<typename F>
void repeat(need_int n, const F& callback){
    for(need_int _ : forrange(n,0)) callback();
}

template<typename T>
struct optional{
    private:
        T *val = nullptr;
        void reserve(){
            val = new T;
        }
    public:
        optional<T> operator=(const T& operand){
            reserve();
            *val = operand;
            return *this;
        }
        bool has_value(){
            return val != nullptr;
        }
        T& value(){
            return *val;
        }
        optional(T val_){
            operator=(val_);
        }
        optional(initializer_list<T> l){
            assert(l.size() == 1);
            operator=(*l.begin());
        }
        optional(){}
};

template<typename T>
optional<T> make_optional(T val_){
    return optional<T>(val_);
}

template<typename T, T(*f)(T,T)>
struct Tracker : optional<T>{
    using optional<T>::operator=;

    Tracker() : optional<T>() {};

    void update(T val){
        if(this->has_value()){
            *this = f(this->value(), val);
        }
        else{
            *this = val;
        }
    }
};

template<typename T>
T min(T a, T b){return std::min(a,b);}
template<typename T>
T max(T a, T b){return std::max(a,b);}
template<typename T>
T __gcd(T a, T b){return std::__gcd(a,b);}

template<typename T, template<typename, typename...> typename Container>
vector<PairOf<T&> > adjecent_pairs(Container<T>& c){
    vector<PairOf<T&> > res;
    optional<T*> prev_elem;
    for(auto& elem : c){
        if(prev_elem.has_value()){
            res.push_back({*prev_elem.value(), elem});
        }
        prev_elem = &elem;
    }
    return res;
}

template<typename T>
struct LazyVector : vector<T>{
    typename vector<T>::reference operator[](counter_type i){
        if(i >= this->size()) this->resize(i+1);
        return vector<T>::operator[](i);
    }
};

template<typename K, typename T>
struct AssocVector : LazyVector<T>{
    LazyVector<bool> exists;
    typename vector<T>::reference operator[](counter_type i){
        exists[i] = true;
        return LazyVector<T>::operator[](i);
    }
    typename vector<T>::iterator find(counter_type i){
        if(!exists[i]) return this->end();
        else return this->begin() + i;
    }
};

template<template<typename, typename, typename...> typename Container, typename Key, typename Value>
bool has_key(Container<Key, Value>& container, Key key){
    return container.find(key) != container.end();
}

template<typename T>
struct Lazy : optional<T>{

    function<T()> f;

    Lazy(function<T()> f) : f{f}, optional<T>() {};

    T& value(){
        if(!this->has_value()){
            optional<T>::operator=(f());
        }
        return optional<T>::value();
    }

};

#define LAZY(val, tipe) mytl::Lazy<tipe>([&](){return (val);})
#define WATCH(x) cout << (#x) << " is " << (x) << endl
}

namespace std{

template<typename T>
istream& operator>>(istream& is, mytl::optional<T>& x){
    if(!x.has_value()){
        T x_;
        is>>x_;
        x = x_;
    }
    return is;
}

istream& operator>>(istream& is, Void& x){
    return is;
}

template<typename P, typename Q>
ostream& operator<<(ostream& os, const pair<P,Q>& x){
    os<<"("<<x.first<<", "<<x.second<<")";
    return os;
}

template<typename T, template<typename, typename...> typename Container>
ostream& operator<<(ostream& os, const Container<T>& x){
    os<<"{";
    bool first = true;
    for(const auto& elem : x){
        if(!first) os<<", ";
        os<<elem;
        first = false;
    }
    os<<"}";
    return os;
}

}

namespace mytl{

template<typename T, typename P=T>
T read(istream& is=cin){
    P a;
    is>>a;
    return T(a);
}

template<typename T, typename P, typename Q>
T read(istream& is=cin){
    P a;
    Q b;
    is>>a>>b;
    return T(a,b);
}

template<typename T, typename P, typename Q, typename R>
T read(istream& is=cin){
    P a;
    Q b;
    R c;
    is>>a>>b>>c;
    return T(a,b,c);
}

template<typename T, typename... Q>
vector<T> readValues(ll n, istream& is=cin){
    vector<T> res;
    repeat(n, [&res](){
        res.push_back(read<T,Q...>());
    });
    return res;
}

}

namespace mytl{

template<typename T>
void print(const T& x, ostream& os=cout){
    os<<x;
}

}
namespace mytl{
template<typename T>
T power(T base, ll exponential, T unit=1){
    T res = unit;
    while(exponential > 0){
        if(exponential%2 == 1) res = res * base;
        base = base * base;
        exponential = exponential / 2;
    }
    return res;
}
}
namespace mytl{
    template<ll MOD>
    struct TSModulo{
    private:
        ll val;

    public:
        static TSModulo inverse(TSModulo x){// asserting MOD is prime
            return power(x, MOD-2);
        };
        TSModulo(ll initVal) : val{(MOD + initVal%MOD)%MOD} {};
        TSModulo() : TSModulo(0) {}
        TSModulo& operator=(const TSModulo&) = default;

        ll get() const{ // no type cast operator to prevent accidentally turning into ordinary number
            return val;
        }

        //Unary operators
        TSModulo operator-() const{
            return TSModulo(-val);
        };
        TSModulo operator+() const{
            return TSModulo(+val);
        };

        //Binary operators on ordinary numbers
        TSModulo operator-(const ll& operand) const{
            return TSModulo(val-operand);
        };
        TSModulo operator+(const ll& operand) const{
            return TSModulo(val+operand);
        };
        TSModulo operator*(const ll& operand) const{
            return TSModulo(val*operand);
        };
        TSModulo operator/(const ll& operand) const{ //asserting MOD is prime
            return TSModulo(inverse(operand) * val);
        };

        //Binary operators on Modulo
        TSModulo operator-(const TSModulo& operand) const{
            return TSModulo(val-operand.get());
        };
        TSModulo operator+(const TSModulo& operand) const{
            return TSModulo(val+operand.get());
        };
        TSModulo operator*(const TSModulo& operand) const{
            return TSModulo(val*operand.get());
        };
        TSModulo operator/(const TSModulo& operand) const{ //asserting MOD is prime
            return TSModulo(val * inverse(operand));
        };
    };

    using Mod107 = TSModulo<1000000007LL>;

    template<ll MOD>
    ostream& operator<<(ostream& os, TSModulo<MOD> x){
        return os<<"("<<x.get()<<"%"<<MOD<<")";
    }

}
namespace mytl{
    struct Modulo{
        static ll global_mod;
    private:
        ll val;
    public:
        const ll MOD;
        Modulo(ll initMOD, ll initVal) : MOD{initMOD}, val{initVal} {
            val %= MOD;
            if(val < 0) val += MOD;
        };
        Modulo() : Modulo(global_mod, 0) {};

        static Modulo inverse(Modulo x){// asserting MOD is prime
            return power(x, x.MOD-2, x.unit());
        };
        Modulo unit() const{
            return Modulo(MOD, 1);
        }
        Modulo& operator=(const Modulo& operand){
            val = operand.val;
            return *this;
        };

        ll get() const{ // no type cast operator to prevent accidentally turning into ordinary number
            return val;
        }

        //Unary operators
        Modulo operator-() const{
            return Modulo(MOD, -val);
        };
        Modulo operator+() const{
            return Modulo(MOD, +val);
        };

        //Binary operators on ordinary numbers
        Modulo operator-(const ll& operand) const{
            return Modulo(MOD, val-operand);
        };
        Modulo operator+(const ll& operand) const{
            return Modulo(MOD, val+operand);
        };
        Modulo operator*(const ll& operand) const{
            return Modulo(MOD, val*operand);
        };
        Modulo operator/(const ll& operand) const{ //asserting MOD is prime
            return Modulo(MOD, val * inverse(Modulo(MOD, operand)).get());
        };

        //Binary operators on Modulo
        Modulo operator-(const Modulo& operand) const{
            return Modulo(MOD, val-operand.get());
        };
        Modulo operator+(const Modulo& operand) const{
            return Modulo(MOD, val+operand.get());
        };
        Modulo operator*(const Modulo& operand) const{
            return Modulo(MOD, val*operand.get());
        };
        Modulo operator/(const Modulo& operand) const{ //asserting MOD is prime
            return Modulo(MOD, val * inverse(operand).get());
        };

    };

    ll Modulo::global_mod = 1000000007LL;

    Modulo mod107(ll x){
        return Modulo(1000000007LL, x);
    }
    ostream& operator<<(ostream& os, Modulo x){
        return os<<"("<<x.get()<<"%"<<x.MOD<<")";
    }

}
namespace mytl {

template<class T>
struct Resetter;

template<class T>
Resetter<T>* global_resetter = new Resetter<T>;

template<class T>
struct Resetter {

    using State = pair<counter_type, T>;

    State* state = new State{0, T()};

    Resetter(){}
    Resetter(T value){
        state = new State{0, value};
    }

    void activate(){
        global_resetter<T> = this;
    }

    void reset(T value){
        *state = State{state->first+1, value};
    }

    struct Variable{

        State state;
        State& parent = *global_resetter<T>->state;

        Variable() : state{*global_resetter<T>->state} {}
        Variable(T value) : state{global_resetter<T>->state->first, value} {}
        Variable(State st) : state{st} {}
        Variable(T value, State& parent) : state{parent->first, value} {};

        bool fresh(){
            return state.first >= parent.first;
        }

        void overwrite(){
            state = parent;
        }

        bool refresh(){
            if(!fresh()) overwrite();
        }

        T get(){
            refresh();
            return state.second;
        }

        void survive(){
            state.first = parent.first;
        }

        void operator=(T new_value){
            state.second = new_value;
            survive();
        }

    };

};
}
namespace mytl{

template<typename N, typename E, template<typename, typename, typename...> typename C>
struct Container_Graph : C<N, vector<pair<E, N> > >{
    template<typename A, typename B>
    using Container = C<A,B>;
    using Edge = E;
    using Node = N;
    optional<ll> n;
    Container_Graph(ll n={}) : n{n}, Container<Node, vector<pair<Edge, Node> > >() {}

    void newEdge(Node u, Node v, Edge edge=Void()){
        (*this)[u].push_back(make_pair(edge, v));
    }
    vector<Node> getNodes(){
        vector<Node> res;
        if(n.has_value()){
            for(ll i=1; i<=n.value(); i++) res.push_back(i);
        }
        else{
            for(auto& p : *this){
                res.push_back(p.first);
            }
        }
        return res;

    }
    vector<pair<Edge, Node> >& getEdges(Node node){
        return (*this)[node];
    }
    vector<Node > getNeighbours(Node node){
        vector<Node> res;
        for(auto& par : getEdges(node)){
            res.push_back(par.second);
        }
        return res;
    }

};

using NormalSimpleGraph = Container_Graph<ll, Void, AssocVector>;

template<typename G>
void readNeighbourList(G& g, ll indexing=1){
    for(ll i : forrange(g.n.size(), indexing)){
        for(ll neig : readValues<ll>(read<ll>())){
            g.new_edge(i, neig);
        }
    }
}

template<typename G>
void readEdgeList(G& g, ll m, bool bidirectional=true){
    using Node = typename G::Node;
    using Edge = typename G::Edge;
    for(auto elem : readValues<tuple<Node, Node, Edge>, Node, Node, Edge >(m)){
        Node u, v;
        Edge edge;
        tie(u, v, edge) = elem;
        g.newEdge(u,v,edge);
        if(bidirectional) g.newEdge(v, u, edge);
    }
}

template<
    typename G,
    template<typename> typename A,
    typename F=void(*)(typename A<G>::Option)
>
typename G::template Container<typename G::Node, typename A<G>::Info> queue_graph_algorithm(
    G& g,
    vector<typename A<G>::Option > sources,
    F new_node_callback=[](typename A<G>::Option){})
{
    using Algo = A<G>;
    typename Algo::Queue q;

    for(auto source : sources) q.push(source);
    typename G::template Container<typename G::Node, typename Algo::Info> d;
    while(!q.empty()){
        auto akt = Algo::consume(q);
        typename Algo::Node who = akt.second;
        typename Algo::Info info = akt.first;

        if(has_key(d, who)) continue;

        d[who] = info;

        new_node_callback({info, who});
        for(auto par : g.getEdges(who)) if(!has_key(d, par.second)){
            q.push({Algo::append({info, who}, par.first, par.second), par.second});
        }
    }
    return d;
}

template<template<typename> typename QP, template<typename> typename P>
struct AlgoComposer{
    template<typename G>
    struct A{
        using Path = P<G>;
        using Edge = typename G::Edge;
        using Node = typename G::Node;
        using Info = typename Path::Info;
        using Option = pair<Info, Node>;
        using QueuePolicy = QP<Option>;
        using Queue = typename QueuePolicy::Queue;

        static Option consume(Queue& q){
            return QueuePolicy::consume(q);
        }
        static void push(Queue& q, Option new_option){
            return QueuePolicy::push(q, new_option);
        }
        static Info append(pair<Info, Node> from , Edge e, Node to){
            return Path::append(from, e, to);
        }
    };
};

template<typename T>
struct Priority{
    using Queue = priority_queue<T, vector<T>, greater<T> >;
    static T consume(Queue& q){
        auto res = q.top();
        q.pop();
        return res;
    }
    static void push(Queue& q, T new_option){
        q.push(new_option);
    }
};

template<typename T>
struct FIFO{
    using Queue = queue<T>;
    static T consume(Queue& q){
        auto res = q.front();
        q.pop();
        return res;
    }
    static void push(Queue& q, T new_option){
        q.push(new_option);
    }
};

template<typename T>
struct FILO{
    using Queue = stack<T>;
    static T consume(Queue& q){
        auto res = q.top();
        q.pop();
        return res;
    }
    static void push(Queue& q, T new_option){
        q.pop();
    }
};

template<typename G>
struct JustLength{
    using Info = typename G::Edge;
    static Info append(pair<Info, typename G::Node> from, typename G::Edge e, typename G::Node n){
        return from.first + e;
    }
};

template<typename G>
struct SimpleJustLength{
    using Info = ll;
    static Info append(pair<Info, typename G::Node> from, typename G::Edge e, typename G::Node n){
        return from.first + 1;
    }
};

template<typename G>
struct LengthAndLastNode{
    using Info = pair<ll, typename G::Node>;
    static Info append(pair<Info, typename G::Node> from, typename G::Edge e, typename G::Node n){
        return Info(from.first + e, from.second);
    }
};

template<typename G>
struct SimpleLengthAndLastNode{
    using Info = pair<ll, typename G::Node>;
    static Info append(pair<Info, typename G::Node> from, typename G::Edge e, typename G::Node n){
        return Info(from.first.first + 1, from.second);
    }
};

/*
template<typename G>
struct Custom{
    using Edge = typename G::Edge;
    using Node = typename G::Node;

    using Info = _;
    using Option = pair<Info, Edge>;
    using Queue = _;

    static Option consume(Queue &q){
        _
        return _;
    }

    static void push(Queue &q, Option new_option){
        _
    }

    static Info append(Option from, Edge e, Node to){
        return _
    }

};
*/
}
namespace mytl{

struct Point{
    ll x, y;

    Point(ll x, ll y) : x{x}, y{y} {};
    Point(pair<ll,ll> initPair) : x{initPair.first}, y{initPair.second} {};

    pair<ll,ll> getPair(){//not introducing type cast operator for safety
        return {x,y};
    }

    //Unary operators
    Point operator-() const{
        return {-x, -y};
    }
    Point operator+() const{
        return {x,y};
    }

    static ll sgn(ll x){
        return (x > 0) - (x < 0);
    }

    //Binary operators on ordinary numbers
    Point operator*(const ll& operand) const{
        return {x*operand, y*operand};
    }

    //Binary operators on Point itself
    Point operator+(const Point& operand) const{
        return {x+operand.x, y+operand.y};
    }
    Point operator-(const Point& operand) const{
        return {x-operand.x, y-operand.y};
    }

    ll operator*(const Point& operand){ //vectorial product
        return x*operand.y - y*operand.x;
    }

    ll direction(const Point& a, const Point& b) const{
        return sgn((a - *this) * (b - *this));
    };
};

ll distance_squared(const Point& a, const Point& b){
    return (a.x-b.x)*(a.x-b.x) + (a.y-b.y)*(a.y-b.y);
}

double distance(const Point& a, const Point& b){
    return sqrt(distance_squared(a, b));
}

ll cartesian_distance(const Point& a, const Point& b){
    return abs(a.x - b.x) + abs(a.y - b.y);
}

typedef vector<Point> Poly;

bool inside(const Poly& poly, const Point& point, bool strict){ //assuming Poly is weakly convex
    ll prevdir = -2;
    for(ll i=0; i<poly.size(); i++){
        ll nexdindex = (i+1)%poly.size();
        ll dir = poly[i].direction(poly[nexdindex], point);
        if(dir == 0){
            if(strict) return false;
        }
        else{
            if(dir != prevdir && prevdir != -2) return false;
            prevdir = dir;
        }

    }
    return true;
}

}
namespace mytl{
template<class Op>
struct Node : Op::Range{
    using Range = typename Op::Range;
    using T = typename Op::T;
    using Change = typename Op::Change;
    using Range::singleton;
    using Range::inside;
    using Range::intersect;
    using Range::leftHalf;
    using Range::rightHalf;

    Node *left_child=NULL, *right_child=NULL;

    T partial;
    Change pending = Op::identity();

    Node(Range range) : Range(range), partial{Op::initial(range)} {};

    T query(Range range, Change change){
        return query_(range, change).first;
    }

    void add(Change change){
        pending = Op::push(pending, change);
    }

    void prepare(){
        if(!singleton()){
            if(left_child == NULL) left_child = (new Node(leftHalf()));
            if(right_child == NULL) right_child = (new Node(rightHalf()));
            left_child->add(pending);
            right_child->add(pending);
        }
        partial = Op::apply(*this, partial, pending);
        pending = Op::identity();
    }

    pair<T,T> query_(Range range, Change change){
        //cout<<range<<" "<<*this<<endl;
        prepare();
        if(inside(range)){
            add(change);
            prepare();
            return {partial, Op::zero()};
        }
        if(!intersect(range)){
            //cout<<"n"<<range<<" "<<*this<<endl;
            return {Op::zero(), partial};
        }

        auto from_left = left_child->query_(range, change);
        auto from_right = right_child->query_(range, change);
        //cout<<from_right.first<<endl;
        auto needed = Op::reduce(from_left.first, from_right.first), rest = Op::reduce(from_left.second, from_right.second);
        partial = Op::reduce(needed, rest);
        return {needed, rest};
    }

    T build_from(const function<T(ll)>& getter){
        prepare();
        pending = Op::identity();
        if(singleton()) partial = getter(this->first);
        else partial = Op::reduce(left_child->build_from(getter), right_child->build_from(getter));
        return partial;
    }

};

struct Range1D : PairOf<ll>{
    using PairOf<ll>::pair;

    ll span() const {
        return second-first+1;
    }
    bool singleton() const {
        return span() == 1;
    }
    Range1D leftHalf() const {
        return Range1D(first, (first+second)/2);
    }
    Range1D rightHalf() const {
        return Range1D((first + second)/2 + 1, second);
    }
    bool inside(const Range1D& other) const {
        return other.first <= first && second <= other.second;
    }
    bool intersect(const Range1D& other) const {

        return other.inside(*this)
             ||(other.first <= first && first <= other.second)
             ||(other.first <= second && second <= other.second);
    }
};

}

namespace mytl{
template<typename T_>
struct Add_Sum{
    using Range = Range1D;
    using T = T_;
    using Change = T_;

    static Change identity(){
        return 0;
    }

    static T zero(){
        return 0;
    }

    static T initial(Range r){
        return zero();
    }

    static T reduce(T a, T b){
        return a + b;
    }

    static T apply(Range r, T a, Change c){
        return a + r.span()*c;
    }

    static Change push(Change a, Change b){
        return a + b;
    }
};

template<typename T_>
struct Multiply_Sum{
    using Range = Range1D;
    using T = T_;
    using Change = T_;

    static Change identity(){
        return 1;
    }

    static T zero(){
        return 0;
    }

    static T initial(Range r){
        return r.span()*1;
    }

    static T reduce(T a, T b){
        return a + b;
    }

    static T apply(Range r, T a, Change c){
        return a*c;
    }

    static Change push(Change a, Change b){
        return a*b;
    }
};

}

namespace mytl{
/*
struct Custom_Op{
    using Range = _;
    using T = _;
    using Change = _;

    static Change identity(){
        return _;
    }

    static T zero(){
        return _;
    }

    static T initial(Range r){
        return _;
    }

    static T reduce(T a, T b){
        return _;
    }

    static T apply(Range r, T a, Change c){
        return _;
    }

    static Change push(Change a, Change b){
        return _;
    }

};
*/

}
namespace mytl{

template <template<typename, typename, typename...> typename C, typename Arg, typename R>
function<R (Arg)> memoize(R (*fn)(Arg)) {
    C<Arg, optional<R> > table;
    return [fn, table](Arg arg) mutable -> R {
        optional<R>& res = table[arg];
        if(!res.has_value()){
            res = fn(arg);
        }
        return res.value();
    };
}

}
//ENDCOPY

using G = mytl::Container_Graph<ll, Void, mytl::AssocVector>;

void processs(){
    ll n;
    cin>>n;
    G g(n);
    mytl::readEdgeList(g, n-1);

        //cout<<"hh";
    auto enyem_ = mytl::readValues<ll>(mytl::read<ll>());
    set<ll> enyem(enyem_.begin(), enyem_.end());
    auto ove_ = mytl::readValues<ll>(mytl::read<ll>());
    set<ll> ove(ove_.begin(), ove_.end());

    //cout<<enyem<<" "<<ove<<endl;
    auto ask = [&](ll& ide, char tipus, ll ki) -> bool{
        cout<<tipus<<" "<<ki<<endl;
        ll got;
        cin>>got;
        if(tipus == 'A' && mytl::has_key(ove, got)){
            cout<<"C "<<ki<<endl;
            return true;
        }
        if(tipus == 'B' && mytl::has_key(enyem, got)){
            cout<<"C "<<got<<endl;
            return true;
        }
        ide = got;
        return false;

    };

    ll one_piece;
    if(ask(one_piece, 'B', *ove.begin())) return;
     vector<pair<pair<ll,ll>, ll> > sour{{{0,-1}, *enyem.begin()}};
    // cout<<sour<<endl;
   auto tb = mytl::queue_graph_algorithm<G, mytl::AlgoComposer<mytl::FILO,mytl::SimpleLengthAndLastNode>::A >(g,sour);

    while(!mytl::has_key(enyem, one_piece)){
        one_piece = tb[one_piece].second;
    }

    ll dc;
    if(ask(dc, 'A', one_piece)) return;
    else{
        cout<<"C -1"<<endl;
    }

}

MAIN main(){
    ll T;
    cin>>T;
    mytl::repeat(T, [&](){
        processs();
    }) ;
}


//STARTCOPY
#include<bits/stdc++.h>
using namespace std;

using u_counter_type = unsigned int;
using need_int = int;
using counter_type = int;
using MAIN = int;
#define int DontUseIntÉ
using ll = long long;

template<typename T>
using PairOf = pair<T,T>;

using Void = tuple<>;

struct BasicInitialization{
    BasicInitialization(){
        ios_base::sync_with_stdio(false);
    }
};
BasicInitialization __basic_initialization__;
namespace mytl{

template<typename T, typename R>
vector<R> fmap(R(*f)(const T), const vector<T>& t){
    vector<R> res;
    for(auto elem : t) res.push_back(f(elem));
    return res;
}

template<typename T>
vector<T> forrange(T n, T from){
    vector<T> res(n);
    iota(res.begin(), res.end(), from);
    return res;
}

template<typename F>
void repeat(need_int n, const F& callback){
    for(need_int _ : forrange(n,0)) callback();
}

template<typename T>
struct optional{
    private:
        T *val = nullptr;
        void reserve(){
            val = new T;
        }
    public:
        optional<T> operator=(const T& operand){
            reserve();
            *val = operand;
            return *this;
        }
        bool has_value(){
            return val != nullptr;
        }
        T& value(){
            return *val;
        }
        optional(T val_){
            operator=(val_);
        }
        optional(initializer_list<T> l){
            assert(l.size() == 1);
            operator=(*l.begin());
        }
        optional(){}
};

template<typename T>
optional<T> make_optional(T val_){
    return optional<T>(val_);
}

template<typename T, T(*f)(T,T)>
struct Tracker : optional<T>{
    using optional<T>::operator=;

    Tracker() : optional<T>() {};

    void update(T val){
        if(this->has_value()){
            *this = f(this->value(), val);
        }
        else{
            *this = val;
        }
    }
};

template<typename T>
T min(T a, T b){return std::min(a,b);}
template<typename T>
T max(T a, T b){return std::max(a,b);}
template<typename T>
T __gcd(T a, T b){return std::__gcd(a,b);}

template<typename T, template<typename, typename...> typename Container>
vector<PairOf<T&> > adjecent_pairs(Container<T>& c){
    vector<PairOf<T&> > res;
    optional<T*> prev_elem;
    for(auto& elem : c){
        if(prev_elem.has_value()){
            res.push_back({*prev_elem.value(), elem});
        }
        prev_elem = &elem;
    }
    return res;
}

template<typename T>
struct LazyVector : vector<T>{
    typename vector<T>::reference operator[](counter_type i){
        if(i >= this->size()) this->resize(i+1);
        return vector<T>::operator[](i);
    }
};

template<typename K, typename T>
struct AssocVector : LazyVector<T>{
    LazyVector<bool> exists;
    typename vector<T>::reference operator[](counter_type i){
        exists[i] = true;
        return LazyVector<T>::operator[](i);
    }
    typename vector<T>::iterator find(counter_type i){
        if(!exists[i]) return this->end();
        else return this->begin() + i;
    }
};

template<template<typename, typename, typename...> typename Container, typename Key, typename Value>
bool has_key(Container<Key, Value>& container, Key key){
    return container.find(key) != container.end();
}

template<typename T>
struct Lazy : optional<T>{

    function<T()> f;

    Lazy(function<T()> f) : f{f}, optional<T>() {};

    T& value(){
        if(!this->has_value()){
            optional<T>::operator=(f());
        }
        return optional<T>::value();
    }

};

#define LAZY(val, tipe) mytl::Lazy<tipe>([&](){return (val);})
#define WATCH(x) cout << (#x) << " is " << (x) << endl
}

namespace std{

template<typename T>
istream& operator>>(istream& is, mytl::optional<T>& x){
    if(!x.has_value()){
        T x_;
        is>>x_;
        x = x_;
    }
    return is;
}

istream& operator>>(istream& is, Void& x){
    return is;
}

template<typename P, typename Q>
ostream& operator<<(ostream& os, const pair<P,Q>& x){
    os<<"("<<x.first<<", "<<x.second<<")";
    return os;
}

template<typename T, template<typename, typename...> typename Container>
ostream& operator<<(ostream& os, const Container<T>& x){
    os<<"{";
    bool first = true;
    for(const auto& elem : x){
        if(!first) os<<", ";
        os<<elem;
        first = false;
    }
    os<<"}";
    return os;
}

}

namespace mytl{

template<typename T, typename P=T>
T read(istream& is=cin){
    P a;
    is>>a;
    return T(a);
}

template<typename T, typename P, typename Q>
T read(istream& is=cin){
    P a;
    Q b;
    is>>a>>b;
    return T(a,b);
}

template<typename T, typename P, typename Q, typename R>
T read(istream& is=cin){
    P a;
    Q b;
    R c;
    is>>a>>b>>c;
    return T(a,b,c);
}

template<typename T, typename... Q>
vector<T> readValues(ll n, istream& is=cin){
    vector<T> res;
    repeat(n, [&res](){
        res.push_back(read<T,Q...>());
    });
    return res;
}

}

namespace mytl{

template<typename T>
void print(const T& x, ostream& os=cout){
    os<<x;
}

}
namespace mytl{
template<typename T>
T power(T base, ll exponential, T unit=1){
    T res = unit;
    while(exponential > 0){
        if(exponential%2 == 1) res = res * base;
        base = base * base;
        exponential = exponential / 2;
    }
    return res;
}
}
namespace mytl{
    template<ll MOD>
    struct TSModulo{
    private:
        ll val;

    public:
        static TSModulo inverse(TSModulo x){// asserting MOD is prime
            return power(x, MOD-2);
        };
        TSModulo(ll initVal) : val{(MOD + initVal%MOD)%MOD} {};
        TSModulo() : TSModulo(0) {}
        TSModulo& operator=(const TSModulo&) = default;

        ll get() const{ // no type cast operator to prevent accidentally turning into ordinary number
            return val;
        }

        //Unary operators
        TSModulo operator-() const{
            return TSModulo(-val);
        };
        TSModulo operator+() const{
            return TSModulo(+val);
        };

        //Binary operators on ordinary numbers
        TSModulo operator-(const ll& operand) const{
            return TSModulo(val-operand);
        };
        TSModulo operator+(const ll& operand) const{
            return TSModulo(val+operand);
        };
        TSModulo operator*(const ll& operand) const{
            return TSModulo(val*operand);
        };
        TSModulo operator/(const ll& operand) const{ //asserting MOD is prime
            return TSModulo(inverse(operand) * val);
        };

        //Binary operators on Modulo
        TSModulo operator-(const TSModulo& operand) const{
            return TSModulo(val-operand.get());
        };
        TSModulo operator+(const TSModulo& operand) const{
            return TSModulo(val+operand.get());
        };
        TSModulo operator*(const TSModulo& operand) const{
            return TSModulo(val*operand.get());
        };
        TSModulo operator/(const TSModulo& operand) const{ //asserting MOD is prime
            return TSModulo(val * inverse(operand));
        };
    };

    using Mod107 = TSModulo<1000000007LL>;

    template<ll MOD>
    ostream& operator<<(ostream& os, TSModulo<MOD> x){
        return os<<"("<<x.get()<<"%"<<MOD<<")";
    }

}
namespace mytl{
    struct Modulo{
        static ll global_mod;
    private:
        ll val;
    public:
        const ll MOD;
        Modulo(ll initMOD, ll initVal) : MOD{initMOD}, val{initVal} {
            val %= MOD;
            if(val < 0) val += MOD;
        };
        Modulo() : Modulo(global_mod, 0) {};

        static Modulo inverse(Modulo x){// asserting MOD is prime
            return power(x, x.MOD-2, x.unit());
        };
        Modulo unit() const{
            return Modulo(MOD, 1);
        }
        Modulo& operator=(const Modulo& operand){
            val = operand.val;
            return *this;
        };

        ll get() const{ // no type cast operator to prevent accidentally turning into ordinary number
            return val;
        }

        //Unary operators
        Modulo operator-() const{
            return Modulo(MOD, -val);
        };
        Modulo operator+() const{
            return Modulo(MOD, +val);
        };

        //Binary operators on ordinary numbers
        Modulo operator-(const ll& operand) const{
            return Modulo(MOD, val-operand);
        };
        Modulo operator+(const ll& operand) const{
            return Modulo(MOD, val+operand);
        };
        Modulo operator*(const ll& operand) const{
            return Modulo(MOD, val*operand);
        };
        Modulo operator/(const ll& operand) const{ //asserting MOD is prime
            return Modulo(MOD, val * inverse(Modulo(MOD, operand)).get());
        };

        //Binary operators on Modulo
        Modulo operator-(const Modulo& operand) const{
            return Modulo(MOD, val-operand.get());
        };
        Modulo operator+(const Modulo& operand) const{
            return Modulo(MOD, val+operand.get());
        };
        Modulo operator*(const Modulo& operand) const{
            return Modulo(MOD, val*operand.get());
        };
        Modulo operator/(const Modulo& operand) const{ //asserting MOD is prime
            return Modulo(MOD, val * inverse(operand).get());
        };

    };

    ll Modulo::global_mod = 1000000007LL;

    Modulo mod107(ll x){
        return Modulo(1000000007LL, x);
    }
    ostream& operator<<(ostream& os, Modulo x){
        return os<<"("<<x.get()<<"%"<<x.MOD<<")";
    }

}
namespace mytl {

template<class T>
struct Resetter;

template<class T>
Resetter<T>* global_resetter = new Resetter<T>;

template<class T>
struct Resetter {

    using State = pair<counter_type, T>;

    State* state = new State{0, T()};

    Resetter(){}
    Resetter(T value){
        state = new State{0, value};
    }

    void activate(){
        global_resetter<T> = this;
    }

    void reset(T value){
        *state = State{state->first+1, value};
    }

    struct Variable{

        State state;
        State& parent = *global_resetter<T>->state;

        Variable() : state{*global_resetter<T>->state} {}
        Variable(T value) : state{global_resetter<T>->state->first, value} {}
        Variable(State st) : state{st} {}
        Variable(T value, State& parent) : state{parent->first, value} {};

        bool fresh(){
            return state.first >= parent.first;
        }

        void overwrite(){
            state = parent;
        }

        bool refresh(){
            if(!fresh()) overwrite();
        }

        T get(){
            refresh();
            return state.second;
        }

        void survive(){
            state.first = parent.first;
        }

        void operator=(T new_value){
            state.second = new_value;
            survive();
        }

    };

};
}
namespace mytl{

template<typename N, typename E, template<typename, typename, typename...> typename C>
struct Container_Graph : C<N, vector<pair<E, N> > >{
    template<typename A, typename B>
    using Container = C<A,B>;
    using Edge = E;
    using Node = N;
    optional<ll> n;
    Container_Graph(ll n={}) : n{n}, Container<Node, vector<pair<Edge, Node> > >() {}

    void newEdge(Node u, Node v, Edge edge=Void()){
        (*this)[u].push_back(make_pair(edge, v));
    }
    vector<Node> getNodes(){
        vector<Node> res;
        if(n.has_value()){
            for(ll i=1; i<=n.value(); i++) res.push_back(i);
        }
        else{
            for(auto& p : *this){
                res.push_back(p.first);
            }
        }
        return res;

    }
    vector<pair<Edge, Node> >& getEdges(Node node){
        return (*this)[node];
    }
    vector<Node > getNeighbours(Node node){
        vector<Node> res;
        for(auto& par : getEdges(node)){
            res.push_back(par.second);
        }
        return res;
    }

};

using NormalSimpleGraph = Container_Graph<ll, Void, AssocVector>;

template<typename G>
void readNeighbourList(G& g, ll indexing=1){
    for(ll i : forrange(g.n.size(), indexing)){
        for(ll neig : readValues<ll>(read<ll>())){
            g.new_edge(i, neig);
        }
    }
}

template<typename G>
void readEdgeList(G& g, ll m, bool bidirectional=true){
    using Node = typename G::Node;
    using Edge = typename G::Edge;
    for(auto elem : readValues<tuple<Node, Node, Edge>, Node, Node, Edge >(m)){
        Node u, v;
        Edge edge;
        tie(u, v, edge) = elem;
        g.newEdge(u,v,edge);
        if(bidirectional) g.newEdge(v, u, edge);
    }
}

template<
    typename G,
    template<typename> typename A,
    typename F=void(*)(typename A<G>::Option)
>
typename G::template Container<typename G::Node, typename A<G>::Info> queue_graph_algorithm(
    G& g,
    vector<typename A<G>::Option > sources,
    F new_node_callback=[](typename A<G>::Option){})
{
    using Algo = A<G>;
    typename Algo::Queue q;

    for(auto source : sources) q.push(source);
    typename G::template Container<typename G::Node, typename Algo::Info> d;
    while(!q.empty()){
        auto akt = Algo::consume(q);
        typename Algo::Node who = akt.second;
        typename Algo::Info info = akt.first;

        if(has_key(d, who)) continue;

        d[who] = info;

        new_node_callback({info, who});
        for(auto par : g.getEdges(who)) if(!has_key(d, par.second)){
            q.push({Algo::append({info, who}, par.first, par.second), par.second});
        }
    }
    return d;
}

template<template<typename> typename QP, template<typename> typename P>
struct AlgoComposer{
    template<typename G>
    struct A{
        using Path = P<G>;
        using Edge = typename G::Edge;
        using Node = typename G::Node;
        using Info = typename Path::Info;
        using Option = pair<Info, Node>;
        using QueuePolicy = QP<Option>;
        using Queue = typename QueuePolicy::Queue;

        static Option consume(Queue& q){
            return QueuePolicy::consume(q);
        }
        static void push(Queue& q, Option new_option){
            return QueuePolicy::push(q, new_option);
        }
        static Info append(pair<Info, Node> from , Edge e, Node to){
            return Path::append(from, e, to);
        }
    };
};

template<typename T>
struct Priority{
    using Queue = priority_queue<T, vector<T>, greater<T> >;
    static T consume(Queue& q){
        auto res = q.top();
        q.pop();
        return res;
    }
    static void push(Queue& q, T new_option){
        q.push(new_option);
    }
};

template<typename T>
struct FIFO{
    using Queue = queue<T>;
    static T consume(Queue& q){
        auto res = q.front();
        q.pop();
        return res;
    }
    static void push(Queue& q, T new_option){
        q.push(new_option);
    }
};

template<typename T>
struct FILO{
    using Queue = stack<T>;
    static T consume(Queue& q){
        auto res = q.top();
        q.pop();
    }
    static void push(Queue& q, T new_option){
        q.pop();
    }
};

template<typename G>
struct JustLength{
    using Info = typename G::Edge;
    static Info append(pair<Info, typename G::Node> from, typename G::Edge e, typename G::Node n){
        return from.first + e;
    }
};

template<typename G>
struct SimpleJustLength{
    using Info = ll;
    static Info append(pair<Info, typename G::Node> from, typename G::Edge e, typename G::Node n){
        return from.first + 1;
    }
};

template<typename G>
struct LengthAndLastNode{
    using Info = pair<ll, typename G::Node>;
    static Info append(pair<Info, typename G::Node> from, typename G::Edge e, typename G::Node n){
        return Info(from.first + e, from.second);
    }
};

template<typename G>
struct SimpleLengthAndLastNode{
    using Info = pair<ll, typename G::Node>;
    static Info append(pair<Info, typename G::Node> from, typename G::Edge e, typename G::Node n){
        return Info(from.first.first + 1, from.second);
    }
};

/*
template<typename G>
struct Custom{
    using Edge = typename G::Edge;
    using Node = typename G::Node;

    using Info = _;
    using Option = pair<Info, Edge>;
    using Queue = _;

    static Option consume(Queue &q){
        _
        return _;
    }

    static void push(Queue &q, Option new_option){
        _
    }

    static Info append(Option from, Edge e, Node to){
        return _
    }

};
*/
}
namespace mytl{

struct Point{
    ll x, y;

    Point(ll x, ll y) : x{x}, y{y} {};
    Point(pair<ll,ll> initPair) : x{initPair.first}, y{initPair.second} {};

    pair<ll,ll> getPair(){//not introducing type cast operator for safety
        return {x,y};
    }

    //Unary operators
    Point operator-() const{
        return {-x, -y};
    }
    Point operator+() const{
        return {x,y};
    }

    static ll sgn(ll x){
        return (x > 0) - (x < 0);
    }

    //Binary operators on ordinary numbers
    Point operator*(const ll& operand) const{
        return {x*operand, y*operand};
    }

    //Binary operators on Point itself
    Point operator+(const Point& operand) const{
        return {x+operand.x, y+operand.y};
    }
    Point operator-(const Point& operand) const{
        return {x-operand.x, y-operand.y};
    }

    ll operator*(const Point& operand){ //vectorial product
        return x*operand.y - y*operand.x;
    }

    ll direction(const Point& a, const Point& b) const{
        return sgn((a - *this) * (b - *this));
    };
};

ll distance_squared(const Point& a, const Point& b){
    return (a.x-b.x)*(a.x-b.x) + (a.y-b.y)*(a.y-b.y);
}

double distance(const Point& a, const Point& b){
    return sqrt(distance_squared(a, b));
}

ll cartesian_distance(const Point& a, const Point& b){
    return abs(a.x - b.x) + abs(a.y - b.y);
}

typedef vector<Point> Poly;

bool inside(const Poly& poly, const Point& point, bool strict){ //assuming Poly is weakly convex
    ll prevdir = -2;
    for(ll i=0; i<poly.size(); i++){
        ll nexdindex = (i+1)%poly.size();
        ll dir = poly[i].direction(poly[nexdindex], point);
        if(dir == 0){
            if(strict) return false;
        }
        else{
            if(dir != prevdir && prevdir != -2) return false;
            prevdir = dir;
        }

    }
    return true;
}

}
namespace mytl{
template<class Op>
struct Node : Op::Range{
    using Range = typename Op::Range;
    using T = typename Op::T;
    using Change = typename Op::Change;
    using Range::singleton;
    using Range::inside;
    using Range::intersect;
    using Range::leftHalf;
    using Range::rightHalf;

    Node *left_child=NULL, *right_child=NULL;

    T partial;
    Change pending = Op::identity();

    Node(Range range) : Range(range), partial{Op::initial(range)} {};

    T query(Range range, Change change){
        return query_(range, change).first;
    }

    void add(Change change){
        pending = Op::push(pending, change);
    }

    void prepare(){
        if(!singleton()){
            if(left_child == NULL) left_child = (new Node(leftHalf()));
            if(right_child == NULL) right_child = (new Node(rightHalf()));
            left_child->add(pending);
            right_child->add(pending);
        }
        partial = Op::apply(*this, partial, pending);
        pending = Op::identity();
    }

    pair<T,T> query_(Range range, Change change){
        //cout<<range<<" "<<*this<<endl;
        prepare();
        if(inside(range)){
            add(change);
            prepare();
            return {partial, Op::zero()};
        }
        if(!intersect(range)){
            //cout<<"n"<<range<<" "<<*this<<endl;
            return {Op::zero(), partial};
        }

        auto from_left = left_child->query_(range, change);
        auto from_right = right_child->query_(range, change);
        //cout<<from_right.first<<endl;
        auto needed = Op::reduce(from_left.first, from_right.first), rest = Op::reduce(from_left.second, from_right.second);
        partial = Op::reduce(needed, rest);
        return {needed, rest};
    }

    T build_from(const function<T(ll)>& getter){
        prepare();
        pending = Op::identity();
        if(singleton()) partial = getter(this->first);
        else partial = Op::reduce(left_child->build_from(getter), right_child->build_from(getter));
        return partial;
    }

};

struct Range1D : PairOf<ll>{
    using PairOf<ll>::pair;

    ll span() const {
        return second-first+1;
    }
    bool singleton() const {
        return span() == 1;
    }
    Range1D leftHalf() const {
        return Range1D(first, (first+second)/2);
    }
    Range1D rightHalf() const {
        return Range1D((first + second)/2 + 1, second);
    }
    bool inside(const Range1D& other) const {
        return other.first <= first && second <= other.second;
    }
    bool intersect(const Range1D& other) const {

        return other.inside(*this)
             ||(other.first <= first && first <= other.second)
             ||(other.first <= second && second <= other.second);
    }
};

}

namespace mytl{
template<typename T_>
struct Add_Sum{
    using Range = Range1D;
    using T = T_;
    using Change = T_;

    static Change identity(){
        return 0;
    }

    static T zero(){
        return 0;
    }

    static T initial(Range r){
        return zero();
    }

    static T reduce(T a, T b){
        return a + b;
    }

    static T apply(Range r, T a, Change c){
        return a + r.span()*c;
    }

    static Change push(Change a, Change b){
        return a + b;
    }
};

template<typename T_>
struct Multiply_Sum{
    using Range = Range1D;
    using T = T_;
    using Change = T_;

    static Change identity(){
        return 1;
    }

    static T zero(){
        return 0;
    }

    static T initial(Range r){
        return r.span()*1;
    }

    static T reduce(T a, T b){
        return a + b;
    }

    static T apply(Range r, T a, Change c){
        return a*c;
    }

    static Change push(Change a, Change b){
        return a*b;
    }
};

}

namespace mytl{
/*
struct Custom_Op{
    using Range = _;
    using T = _;
    using Change = _;

    static Change identity(){
        return _;
    }

    static T zero(){
        return _;
    }

    static T initial(Range r){
        return _;
    }

    static T reduce(T a, T b){
        return _;
    }

    static T apply(Range r, T a, Change c){
        return _;
    }

    static Change push(Change a, Change b){
        return _;
    }

};
*/

}
namespace mytl{

template <template<typename, typename, typename...> typename C, typename Arg, typename R>
function<R (Arg)> memoize(R (*fn)(Arg)) {
    C<Arg, optional<R> > table;
    return [fn, table](Arg arg) mutable -> R {
        optional<R>& res = table[arg];
        if(!res.has_value()){
            res = fn(arg);
        }
        return res.value();
    };
}

}
//ENDCOPY

using G = mytl::Container_Graph<ll, Void, mytl::AssocVector>;

void processs(){
    ll n;
    cin>>n;
    G g(n);
    mytl::readEdgeList(g, n-1);

        cout<<"hh";
    auto enyem_ = mytl::readValues<ll>(mytl::read<ll>());
    set<ll> enyem(enyem_.begin(), enyem_.end());
    auto ove_ = mytl::readValues<ll>(mytl::read<ll>());
    set<ll> ove(ove_.begin(), ove_.end());
    auto ask = [&](ll& ide, char tipus, ll ki) -> bool{
        cout<<tipus<<" "<<ki<<endl;
        ll got;
        cin>>got;
        if(tipus == 'A' && mytl::has_key(ove, got)){
            cout<<"C "<<ki<<endl;
            return true;
        }
        if(tipus == 'B' && mytl::has_key(enyem, got)){
            cout<<"C "<<got<<endl;
            return true;
        }
        ide = got;
        return false;

    };

    ll one_piece;
    if(ask(one_piece, 'B', *ove.begin())) return;

    auto tb = mytl::queue_graph_algorithm<G, mytl::AlgoComposer<mytl::FILO,mytl::SimpleLengthAndLastNode>::A >(g, vector<pair<pair<ll,ll>, ll> >{{{0,-1}, *enyem.begin()}});

    while(!mytl::has_key(enyem, one_piece)){
        one_piece = tb[one_piece].second;
    }

    ll dc;
    if(ask(dc, 'A', one_piece)) return;
    else{
        cout<<"C -1"<<endl;
    }

}

MAIN main(){
    ll T;
    cin>>T;
    mytl::repeat(T, [&](){
        processs();
    }) ;
}