#include <bits/stdc++.h>
#include <cassert>
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx,avx2,fma")
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
#define MAX 1010100
#define MAXS 17
#define INF 10000000000000
#define bb ' '
#define ln '\n'
#define Ln '\n'
pii operator+(pii p1, pii p2) {
if (!~p1.first) return p2;
if (!~p2.first) return p1;
return pii(min(p1.first, p2.first), max(p1.second, p2.second));
}
void operator+=(pii& p1, pii p2) { p1 = p1 + p2; }
pii operator+(pii p1, int x) {
if (!~p1.first) return p1;
return pii(p1.first + x, p1.second + x);
}
void operator+=(pii& p1, int x) { p1 = p1 + x; }
bool ison(pii p, int x) { return p.first <= x && x <= p.second; }
pii dp[2][MAX];
int arr[2][MAX];
int ans[MAX];
signed main() {
ios::sync_with_stdio(false), cin.tie(0);
int N;
cin >> N;
int i;
for (i = 1; i <= N * 2; i++) cin >> arr[0][i];
for (i = 1; i <= N * 2; i++) cin >> arr[1][i];
for (i = 1; i <= N * 2; i++) dp[0][i] = dp[1][i] = pii(-1, -1);
dp[0][0] = pii(-1, N * 2);
dp[1][0] = pii(-1, N * 2);
dp[0][1] = pii(0, 0);
dp[1][1] = pii(1, 1);
for (i = 2; i <= N * 2; i++) for (auto c : { 0, 1 }) for (auto p : { 0, 1 }) if (arr[p][i - 1] <= arr[c][i]) dp[c][i] += dp[p][i - 1] + c;
auto resintv = dp[0][N * 2] + dp[1][N * 2];
if (!ison(resintv, N)) {
cout << -1 << ln;
return 0;
}
int pv = 1e9 + 10;
int rem = N;
for (i = N * 2; i >= 1; i--) {
int c;
for (c = 0; c < 2; c++) {
if (arr[c][i] > pv) continue;
int chk = 0;
for (auto p : { 0, 1 }) if (((i - 1) >= (rem - c)) && arr[p][i - 1] <= arr[c][i] && ison(dp[p][i - 1], rem - c)) chk = 1;
if (chk) break;
}
pv = arr[c][i];
ans[i] = c;
rem -= c;
}
for (i = 1; i <= N * 2; i++) cout << (!ans[i] ? 'A' : 'B');
}
