#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 1e6 + 2;
const int inf = 1e9;
int a[N][2], dpl[N][2], dpr[N][2], ans[N];
void Resi(int i, int j, int k) {
if (i == 0) return;
ans[i] = j;
k -= j;
if (dpl[i - 1][0] <= k && k <= dpr[i - 1][0] && a[i - 1][0] <= a[i][j]) Resi(i - 1, 0, k);
else if (dpl[i - 1][1] <= k && k <= dpr[i - 1][1] && a[i - 1][1] <= a[i][j]) Resi(i - 1, 1, k);
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n; cin >> n;
n = 2 * n;
for (int i = 1; i <= n; i++) cin >> a[i][0];
for (int i = 1; i <= n; i++) cin >> a[i][1];
for (int i = 1; i <= n; i++) for (int j = 0; j < 2; j++) dpl[i][j] = inf, dpr[i][j] = -inf;
dpl[1][0] = dpr[1][0] = 0;
dpl[1][1] = dpr[1][1] = 1;
for (int i = 2; i <= n; i++) {
for (int j = 0; j < 2; j++) {
for (int pj = 0; pj < 2; pj++) {
if (a[i - 1][pj] > a[i][j]) continue;
smin(dpl[i][j], dpl[i - 1][pj] + j);
smax(dpr[i][j], dpr[i - 1][pj] + j);
}
}
}
if (dpl[n][0] <= n / 2 && n / 2 <= dpr[n][0]) Resi(n, 0, n / 2);
else if (dpl[n][1] <= n / 2 && n / 2 <= dpr[n][1]) Resi(n, 1, n / 2);
else {cout << -1; return 0;}
for (int i = 1; i <= n; i++) {
if (ans[i] == 0) cout << 'A';
if (ans[i] == 1) cout << 'B';
}
cout << en;
return 0;
}
