#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <set>
#include <stdlib.h>
#include <map>
#include <random>
#include <cstring>
#include <functional>
#include <iomanip>
#include <cassert>
#include <queue>
#include <unordered_map>
#include <unordered_set>
#include <array>
using namespace std;
#define int long long
const int inf = 1e9;
void solve() {
int n;
cin >> n;
n *= 2;
vector<int> a(n);
vector<int> b(n);
for (int& i : a) cin >> i;
for (int& i : b) cin >> i;
pair<int, int> dp[n][2];
for (int i = 0; i < n; ++i) {
dp[i][0] = dp[i][1] = { inf, -inf };
}
dp[0][0] = { 1, 1 };
dp[0][1] = { 0, 0 };
auto f = [&] (pair<int, int> x, pair<int, int> y, int offset) { return make_pair(min(x.first, y.first + offset), max(x.second, y.second + offset)); };
for (int i = 0; i + 1 < n; ++i) {
if (a[i + 1] >= a[i]) dp[i + 1][0] = f(dp[i + 1][0], dp[i][0], 1);
if (a[i + 1] >= b[i]) dp[i + 1][0] = f(dp[i + 1][0], dp[i][1], 1);
if (b[i + 1] >= a[i]) dp[i + 1][1] = f(dp[i + 1][1], dp[i][0], 0);
if (b[i + 1] >= b[i]) dp[i + 1][1] = f(dp[i + 1][1], dp[i][1], 0);
}
vector<int> res;
int ptr = n - 1;
int can = n / 2;
int pr = inf;
while (ptr >= 0) {
if (dp[ptr][0].first <= can && can <= dp[ptr][0].second && a[ptr] <= pr) {
res.push_back(0);
pr = a[ptr];
--can;
} else if (dp[ptr][1].first <= can && can <= dp[ptr][1].second && b[ptr] <= pr) {
res.push_back(1);
pr = b[ptr];
} else {
cout << -1;
return;
}
--ptr;
}
reverse(res.begin(), res.end());
const vector<char> lets = { 'A', 'B' };
for (int i : res) {
cout << lets[i];
}
}
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int t;
t = 1;
while (t--) {
solve();
}
}
/*
3
2 5 4 9 15 11
6 7 6 8 12 14
*/
