#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
mt19937 rnd(chrono::high_resolution_clock::now().time_since_epoch().count());
const int N = 5e5 + 7;
const int inf = 1e9 + 7;
pair <int, int> dp[2 * N][2];
int a[2 * N][2];
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
n *= 2;
for (int i = 0; i < n; i++) {
cin >> a[i][0];
}
for (int i = 0; i < n; i++) {
cin >> a[i][1];
}
for (int i = 0; i < n; i++) {
for (int j = 0; j < 2; j++) {
dp[i][j] = {inf, -1};
}
}
dp[0][0] = {1, 1};
dp[0][1] = {0, 0};
for (int i = 1; i < n; i++) {
for (int me = 0; me < 2; me++) {
for (int was = 0; was < 2; was++) {
if (a[i - 1][was] > a[i][me]) {
continue;
}
dp[i][me].first = min(dp[i][me].first, dp[i - 1][was].first + (me == 0));
dp[i][me].second = max(dp[i][me].second, dp[i - 1][was].second + (me == 0));
}
}
}
int need = n / 2;
string ans;
if (dp[n - 1][0].first > need || dp[n - 1][0].second < need) {
if (dp[n - 1][1].first > need || dp[n - 1][1].second < need) {
cout << -1 << '\n';
return 0;
}
}
int need_a = need, need_b = need;
int last = inf;
for (int i = n - 1; i >= 0; i--) {
if (dp[i][0].first <= need_a && dp[i][0].second >= need_a && a[i][0] <= last) {
ans += 'A';
need_a--;
last = a[i][0];
} else {
ans += 'B';
need_b--;
last = a[i][1];
}
}
reverse(ans.begin(), ans.end());
cout << ans << '\n';
return 0;
}
