#include <bits/stdc++.h>
using namespace std;
template <class X, class Y>
bool cmin(X &a, const Y &b) {
return a > b ? a = b, 1 : 0;
}
template <class X, class Y>
bool cmax(X &a, const Y &b) {
return a < b ? a = b, 1 : 0;
}
const int N = 1000005;
int mn[N][2], mx[N][2], a[N][2];
void trace(int n, int c) {
}
int main() {
cin.tie(0)->sync_with_stdio(0);
int n; 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];
mn[1][1] = mx[1][1] = 1;
for (int i = 2; i <= n * 2; i++) {
mn[i][0] = mn[i][1] = 2 * n + 1;
for (int c1 = 0; c1 < 2; c1++)
for (int c2 = 0; c2 < 2; c2++)
if (a[i - 1][c1] <= a[i][c2]) {
cmin(mn[i][c2], mn[i - 1][c1] + c2);
cmax(mx[i][c2], mx[i - 1][c1] + c2);
}
}
int c, cnt = n;
if (mn[2 * n][0] <= n && n <= mx[2 * n][0]) c = 0;
else if (mn[2 * n][1] <= n && n <= mx[2 * n][1]) c = 1;
else return cout << "-1\n", 0;
n *= 2; string ans(n, 'A');
while (true) {
cnt -= c; ans[n - 1] = 'A' + c;
if (n == 1) break;
if (a[n][c] >= a[n - 1][1] && mn[n - 1][1] <= cnt
&& cnt <= mx[n - 1][1]) c = 1;
else c = 0;
n--;
}
cout << ans << '\n';
}
