#include <bits/stdc++.h>
using namespace std;
int main()
{
cin.tie(nullptr)->sync_with_stdio(0);
int n;
cin >> n;
vector<int> a(2 * n), b(2 * n);
for(int &i : a) {
cin >> i;
}
for(int &i : b) {
cin >> i;
}
const int oo = 1e9;
vector<vector<pair<int, int>>> dp(2 * n, vector<pair<int, int>>(2, {oo, -oo}));
dp[0][0] = {1, 1};
dp[0][1] = {0, 0};
auto merge = [&](pair<int, int> &one, pair<int, int> &two, int offset) {
one = {min(one.first, two.first + offset), max(one.second, two.second + offset)};
};
for(int i = 0; i < 2 * n - 1; i++) {
if(a[i] <= a[i + 1]) merge(dp[i + 1][0], dp[i][0], 1);
if(a[i] <= b[i + 1]) merge(dp[i + 1][1], dp[i][0], 0);
if(b[i] <= a[i + 1]) merge(dp[i + 1][0], dp[i][1], 1);
if(b[i] <= b[i + 1]) merge(dp[i + 1][1], dp[i][1], 0);
}
int used = n, nxt = oo;
string ans(2 * n, '?');
for(int i = 2 * n - 1; i >= 0; i--) {
if(dp[i][0].first <= used && used <= dp[i][0].second && a[i] <= nxt) {
ans[i] = 'A';
used--;
nxt = a[i];
}
else if(dp[i][1].first <= used && used <= dp[i][1].second && b[i] <= nxt) {
ans[i] = 'B';
nxt = b[i];
}
else {
cout << "-1" << '\n';
exit(0);
}
}
cout << ans << '\n';
}
