#include <bits/stdc++.h>
using namespace std;
#define sz(v) int(v.size())
#define ar array
typedef long long ll;
const int N = 1e6+10, MOD = 1e9+7;
// some are switchable, but only if the next thing switches (or if it's the tail end)
// you can just start from the end and swithc stuff while you need to
int n, a[N][2];
ar<int, 2> dp[N][2];
void add_self(ar<int, 2>& x, ar<int, 2> y, int delta) {
y[0] += delta;
y[1] += delta;
x[0] = min(x[0], y[0]);
x[1] = max(x[1], y[1]);
}
void solve() {
cin >> n;
for (int j = 0; j < 2; j++) {
for (int i = 0; i < 2 * n; i++) cin >> a[i][j];
}
dp[0][0] = {-1, -1};
dp[0][1] = {1, 1};
for (int i = 1; i < 2 * n; i++) {
// 1 if you take b, -1 if you take a
dp[i][0] = {MOD, -MOD};
dp[i][1] = {MOD, -MOD};
for (int x = 0; x < 2; x++) {
for (int y = 0; y < 2; y++) {
if (a[i-1][x] <= a[i][y]) {
add_self(dp[i][y], dp[i-1][x], (y ? +1 : -1));
}
}
}
}
int last = -1;
for (int x : {0, 1}) if (dp[2*n-1][x][0] <= 0 && 0 <= dp[2*n-1][x][1]) last = x;
if (last == -1) {
cout << -1 << '\n';
return;
}
string ans(2 * n, '?');
int start = 0;
for (int i = 2*n-1; i >= 0; i--) {
ans[i] = last + 'A';
if (!i) break;
start -= (last ? +1 : -1);
for (int x : {0, 1}) {
if (a[i-1][x] <= a[i][last] && dp[i-1][x][0] <= start && start <= dp[i-1][x][1]) {
last = x;
break;
}
}
}
cout << ans << '\n';
}
int main() {
ios::sync_with_stdio(false); cin.tie(0);
int T = 1;
// cin >> T;
while (T--) solve();
}
