#include <bits/stdc++.h>
using namespace std;
#define int long long
const int MAXN = 2001;
int prec[MAXN * 2][MAXN][2];
int A[MAXN * 2];
int B[MAXN * 2];
int N;
void dp(int posActu , int score , int iEtage)
{
//cout<<posActu<<" "<<score<<" "<<iEtage<<endl;
if (posActu == 2 * N -1)
{
return;
}
if (iEtage == 0)
{
if (score < N && prec[posActu + 1][score + 1][0] == -1 && A[posActu] <= A[posActu + 1])
{
// cout<<"QergqreGQ"<<endl;
prec[posActu + 1][score + 1][0] = 1;
dp(posActu + 1 , score + 1 , 0);
}
if (prec[posActu + 1][score][1] == -1 && A[posActu] <= B[posActu + 1])
{
prec[posActu + 1][score][1] = 2;
dp(posActu + 1 , score , 1);
}
}
else
{
if (score < N && prec[posActu + 1][score + 1][0] == -1 && B[posActu] <= A[posActu + 1])
{
// cout<<"QeroogqreGQ"<<endl;
prec[posActu + 1][score + 1][0] = 2;
dp(posActu + 1 , score + 1 , 0);
}
if (prec[posActu + 1][score][1] == -1 && B[posActu] <= B[posActu + 1])
{
prec[posActu + 1][score][1] = 1;
dp(posActu + 1 , score , 1);
}
}
}
int32_t main()
{
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> N;
for (int i = 0 ; i < N * 2 ; i++)
{
cin >> A[i];
}
for (int i = 0 ; i < N * 2 ; i++)
{
cin >> B[i];
}
for (int i = 0 ; i < MAXN * 2 ; i++)
{
for (int j = 0 ; j < MAXN ; j++)
{
prec[i][j][0] = prec[i][j][1] = -1;
}
}
dp(0 , 1 , 0);
dp(0 , 0 , 1);
int posActu = 0;
if (prec[2 * N - 1][N][0] != -1)
{
posActu = 0;
}
else if (prec[2* N - 1][N][1] != -1)
{
posActu = 1;
}
else
{
cout<<-1<<endl;
exit(0);
}
vector <int> sol;
int scoreActu = N;
for (int i = 0 ; i < 2 * N ; i++)
{
//cout<<i<<" e"<<posActu<<" "<<scoreActu<<" "<<prec[2 * N -1 - i][scoreActu][posActu]<<" "<<2 * N - 1 - i<<endl;
sol.push_back(posActu);
if (i < 2 * N - 1)
{
int pp = posActu;
if (prec[2 * N - 1 - i][scoreActu][posActu] == 2)
{
// cout<<"a"<<endl;
posActu = 1 - posActu;
}
scoreActu -= (pp == 0);
}
}
for (int i = 2 * N -1 ; i >= 0 ; i--)
{
if (sol[i] == 0) cout<<"A";
else cout<<"B";
}
cout<<endl;
/*for (int k = 0 ; k < 2 ; k++)
{
for (int i = 0 ; i < 2 * N ; i++)
{
for (int j = 0 ; j <= N ; j++)
{
cout<<prec[i][j][k]<<" ";
}
cout<<endl;
}
cout<<endl;
}*/
}
