#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 7, inf = 1e9 + 9;
int n, a[N][2];
int mn[N][2], mx[N][2];
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n;
for (int i = 1; i <= 2 * n; ++i)
cin >> a[i][0];
for (int i = 1; i <= 2 * n; ++i)
cin >> a[i][1];
for (int i = 1; i <= 2 * n; i++) {
mn[i][0] = mn[i][1] = inf;
mx[i][0] = mx[i][1] = -inf;
}
for (int i = 1; i <= 2 * n; i++) {
for (int j = 0; j < 2; j++) {
for (int k = 0; k < 2; k++) {
if (a[i - 1][k] <= a[i][j]) {
if (mn[i - 1][k] != inf)
mn[i][j] = min(mn[i][j], mn[i - 1][k] + j);
if (mx[i - 1][k] != -inf)
mx[i][j] = max(mx[i][j], mx[i - 1][k] + j);
}
}
}
}
int j = -1;
for (int i = 0; i < 2; i++) {
if (mn[2 * n][i] <= n && n <= mx[2 * n][i]) {
j = i;
break;
}
}
if (j == -1) {
cout << -1;
return 0;
}
string ans;
int cur = n;
for (int i = 2 * n; i; i--) {
cur -= j;
ans.push_back('A' + j);
int jj = -1;
for (int k = 0; k < 2; k++) {
if (mn[i - 1][k] <= cur && cur <= mx[i - 1][k] && a[i - 1][k] <= a[i][j]) {
jj = k;
break;
}
}
j = jj;
}
reverse(ans.begin(), ans.end());
cout << ans << endl;
return 0;
}
