//#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
#define ve vector
typedef long long ll;
typedef pair<int, int> pii;
const int INF = 1e9 + 10;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n, r, v;
ve<int> A, B;
ve<pii> Ap, Bp;
ve<bool> Sol;
cin >> n;
A = ve<int>(2 * n);
B = ve<int>(2 * n);
Ap = ve<pii>(2 * n, { INF, -INF });
Bp = ve<pii>(2 * n, { INF, -INF });
Sol = ve<bool>(2 * n);
for (int i = 0; i < 2 * n; i++) cin >> A[i];
for (int i = 0; i < 2 * n; i++) cin >> B[i];
Ap[0] = {1, 1};
Bp[0] = {0, 0};
for (int i = 1; i < 2 * n; i++) {
if (A[i - 1] <= A[i]) {
Ap[i] = {min(Ap[i].first, Ap[i - 1].first), max(Ap[i].second, Ap[i - 1].second)};
}
if (B[i - 1] <= A[i]) {
Ap[i] = {min(Ap[i].first, Bp[i - 1].first), max(Ap[i].second, Bp[i - 1].second)};
}
if (A[i - 1] <= B[i]) {
Bp[i] = {min(Bp[i].first, Ap[i - 1].first), max(Bp[i].second, Ap[i - 1].second)};
}
if (B[i - 1] <= B[i]) {
Bp[i] = {min(Bp[i].first, Bp[i - 1].first), max(Bp[i].second, Bp[i - 1].second)};
}
if (Ap[i].first != INF) {
Ap[i].first++;
Ap[i].second++;
}
}
if (Ap[2 * n - 1].first <= n && n <= Ap[2 * n - 1].second) r = 0;
else if (Bp[2 * n - 1].first <= n && n <= Bp[2 * n - 1].second) r = 1;
else r = -1;
if (r == -1) cout << -1 << endl;
else {
Sol[2 * n - 1] = r;
v = n;
for (int i = 2 * n - 2; i >= 0; i--) {
if (r == 0) {
v--;
if (A[i] <= A[i + 1] && Ap[i].first <= v && v <= Ap[i].second) r = 0;
else r = 1;
}
else {
if (A[i] <= B[i + 1] && Ap[i].first <= v && v <= Ap[i].second) r = 0;
else r = 1;
}
Sol[i] = r;
}
for (int i = 0; i < 2 * n; i++) {
if (Sol[i] == 0) cout << "A";
else cout << "B";
}
cout << endl;
}
return 0;
}
