/* In the name of God, aka Allah */
// let this be mytemp.cpp
#include<bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define endl '\n'
#define mk make_pair
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int N = 2e6 + 50;
int n, a[N];
pii dp[N];
void solve() {
cin >> n;
n <<= 1;
for (int i = 1; i <= n; i++) {
cin >> a[i<<1];
}
for (int i = 1; i <= n; i++) {
cin >> a[i<<1|1];
}
dp[n<<1] = {0, 0};
dp[n<<1|1] = {1, 1};
for (int i = (n<<1)-1; i >= 0; i--) {
dp[i] = {N, -N};
int x = i+2, y = x^1;
if (a[i] <= a[x]) {
dp[i].F = min(dp[i].F, dp[x].F+(i&1));
dp[i].S = max(dp[i].S, dp[x].S+(i&1));
}
if (a[i] <= a[y]) {
dp[i].F = min(dp[i].F, dp[y].F+(i&1));
dp[i].S = max(dp[i].S, dp[y].S+(i&1));
}
}
if (dp[0].F > n/2 || dp[0].S < n/2) return cout << -1 << endl, void();
int cur = n/2;
int u = 0;
for (int x = 1; x <= n; x++) {
if (a[u] <= a[x<<1] && dp[x<<1].F <= cur && cur <= dp[x<<1].S) {
cout << 'A';
u = x<<1;
}
else {
cout << 'B';
u = x<<1|1;
cur--;
}
}
cout << endl;
}
int main() {
ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
solve();
return 0;
}
