#include <bits/stdc++.h>
using namespace std;
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
n *= 2;
vector<int> a(n + 1, 0), b(n + 1, 0);
for (int i = 1; i <= n; i++) cin >> a[i];
for (int i = 1; i <= n; i++) cin >> b[i];
vector<vector<int>> dp_max(2, vector<int>(n + 1, -1));
vector<vector<int>> dp_min(2, vector<int>(n + 1, n + 1));
dp_max[0][0] = dp_max[1][0] = dp_min[0][0] = dp_min[1][0] = 0;
for (int i = 0; i < n; i++) {
if (a[i + 1] >= a[i]) {
if (dp_max[0][i] >= 0) dp_max[0][i + 1] = max(dp_max[0][i + 1], dp_max[0][i] + 1);
if (dp_min[0][i] <= n) dp_min[0][i + 1] = min(dp_min[0][i + 1], dp_min[0][i] + 1);
}
if (a[i + 1] >= b[i]) {
if (dp_max[1][i] >= 0) dp_max[0][i + 1] = max(dp_max[0][i + 1], dp_max[1][i] + 1);
if (dp_min[1][i] <= n) dp_min[0][i + 1] = min(dp_min[0][i + 1], dp_min[1][i] + 1);
}
if (b[i + 1] >= b[i]) {
if (dp_max[1][i] >= 0) dp_max[1][i + 1] = max(dp_max[1][i + 1], dp_max[1][i]);
if (dp_min[1][i] <= n) dp_min[1][i + 1] = min(dp_min[1][i + 1], dp_min[1][i]);
}
if (b[i + 1] >= a[i]) {
if (dp_max[0][i] >= 0) dp_max[1][i + 1] = max(dp_max[1][i + 1], dp_max[0][i]);
if (dp_min[0][i] <= n) dp_min[1][i + 1] = min(dp_min[1][i + 1], dp_min[0][i]);
}
}
int cur = -1;
for (int i = 0; i < 2; i++) {
if (dp_max[i][n] < n / 2 || dp_min[i][n] > n / 2) continue;
cur = i;
}
if (cur == -1) return cout << -1, 0;
string ans = "";
int need = n / 2;
for (int i = n; i >= 1; i--) {
ans += cur ? 'B' : 'A';
int v = cur ? b[i] : a[i];
need -= cur ^ 1;
if (a[i - 1] <= v && dp_min[0][i - 1] <= need && need <= dp_max[0][i - 1]) {
cur = 0;
} else {
assert(b[i - 1] <= v && dp_min[1][i - 1] <= need && need <= dp_max[1][i - 1]);
cur = 1;
}
}
reverse(ans.begin(), ans.end());
cout << ans;
}
