#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define all(v) begin(v), end(v)
#define pi pair<int, int>
#define vi vector<int>
using namespace std;
const int N = 1e6+3;
int a[N][2], n;
pair<int, int> dp[N][2];
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n;
for(int i = 0; i < 2; i++){
for(int j = 1; j <= n*2; j++) cin >> a[j][i];
}
for(int j = 1; j <= n * 2; j++){
for (int i = 0; i < 2; i++){
dp[j][i] = {1e9, -1e9};
for(int u = 0; u <= 1; u++){
if(a[j-1][u] <= a[j][i]){
dp[j][i].first = min(dp[j][i].first, dp[j-1][u].first + i);
dp[j][i].second = max(dp[j][i].second, dp[j-1][u].second + i);
}
}
}
}
if (!(dp[n * 2][0].first <= n && n <= dp[n * 2][0].second)
&& !(dp[n * 2][1].first <= n && n <= dp[n * 2][1].second)){
cout << -1;
return 0;
}
bool cur = 0;
int cnt = n;
a[n * 2 + 1][0] = 1e9;
string ans;
for(int i = n * 2; i >= 1; i--){
for(int j = 0; j <= 1; j++){
if(a[i + 1][cur] >= a[i][j] && dp[i][j].first <= cnt && cnt <= dp[i][j].second){
cur = j;
break;
}
}
ans += 'A' + cur;
cnt -= cur;
}
reverse(all(ans));
cout << ans;
return 0;
}
