#include <bits/stdc++.h>
using namespace std;
int N, A[1000001][2], L[1000001][2], R[1000001][2];
int main() {
ios_base::sync_with_stdio(0), cin.tie(0);
cin >> N;
for (int i = 1; i <= N * 2; ++i) cin >> A[i][0];
for (int i = 1; i <= N * 2; ++i) cin >> A[i][1];
for (int i = 1; i <= N * 2; ++i) {
L[i][0] = L[i][1] = 1e9;
R[i][0] = R[i][1] = -1e9;
for (int j = 0; j < 2; ++j) {
for (int k = 0; k < 2; ++k) {
if (A[i - 1][j] <= A[i][k]) {
L[i][k] = min(L[i][k], L[i - 1][j] + (k == 0));
R[i][k] = max(R[i][k], R[i - 1][j] + (k == 0));
}
}
}
}
string ans;
int a = 0, pre = 1e9;
for (int i = N * 2; i >= 1; --i) {
if (pre >= A[i][0] && L[i][0] <= N - a && N - a <= R[i][0]) {
pre = A[i][0];
ans += 'A';
++a;
continue;
}
if (pre >= A[i][1] && L[i][1] <= N - a && N - a <= R[i][1]) {
pre = A[i][1];
ans += 'B';
continue;
}
return !printf("-1");
}
reverse(ans.begin(), ans.end());
cout << ans;
return 0;
}
