#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define all(aaa) aaa.begin(), aaa.end()
const int N = 4005;
int dp[N][N], a[2][N], ans[N];
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n;
cin >> n;
for (int i = 0; i < 2; i++) {
for (int j = 0; j < n + n; j++) {
cin >> a[i][j];
}
}
memset(dp, -1, sizeof(dp));
dp[1][0] = 0;
dp[1][1] = 1;
for (int i = 1; i < n + n; i++) {
for (int j = 0; j <= n; j++) {
if (dp[i][j] != -1) {
for (int k = 0; k <= min(1, n - j); k++) {
if (a[dp[i][j]][i - 1] <= a[k][i]) {
if (dp[i + 1][j + k] == -1 ||
a[dp[i + 1][j + k]][i] > a[k][i]) {
dp[i + 1][j + k] = k;
}
}
}
}
}
}
// cout << dp[1][0] << "\n";
if (dp[n + n][n] == -1) {
cout << "-1";
}
else {
int x = n + n, y = n;
while (x > 0) {
ans[x - 1] = dp[x][y];
y -= dp[x][y];
x--;
}
for (int i = 0; i < n + n; i++) {
cout << (ans[i] ? 'B' : 'A');
}
}
return 0;
}
