#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f;
#define all(x) x.begin(), x.end()
#define ms(x, a) memset(x, a, sizeof(x))
//===========================================
const int MAX = 2005;
int a[MAX], b[MAX], dp[2][MAX][MAX];
int main(){
cin.tie(0)->sync_with_stdio(0);
int n; cin >> n; n*=2;
for (int i = 1; i <= n; i++) cin >> a[i];
for (int i = 1; i <= n; i++) cin >> b[i];
dp[0][0][0] = -1;
for (int i = 1; i <= n; i++){
for (int j = 0; j <= n; j++){
if (j && a[i] >= a[i-1] && dp[0][i-1][j-1])
dp[0][i][j] = 1;
if (j && a[i] >= b[i-1] && dp[1][i-1][j-1])
dp[0][i][j] = 2;
if (b[i] >= a[i-1] && dp[0][i-1][j])
dp[1][i][j] = 1;
if (b[i] >= b[i-1] && dp[1][i-1][j])
dp[1][i][j] = 2;
}
}
if (dp[0][n][n/2] || dp[1][n][n/2]){
string res = "";
int c = (dp[0][n][n/2]? 0 : 1), rem = n/2;
for (int i = n; i; i--){
res += (c? 'B' : 'A');
c = dp[c][i][rem]-1;
if (res.back() == 'A') rem--;
}
reverse(all(res));
cout << res << "\n";
return 0;
}
cout << -1 << "\n";
}
