#include <bits/stdc++.h>
using namespace std;
const int N = 5e5 + 3;
pair<int, int> dp[N][2];
int n, a[2][N];
pair<int, int> merge(const pair<int, int> &l, const pair<int, int> &r){
if(l == pair{1, 0} || r == pair{1, 0}) return (l == pair{1, 0}) ? r : l;
return {min(l.first, r.first), max(l.second, r.second)};
}
void output(int i, int j, int target = n / 2){
if(i == 0) return;
target -= j;
if(dp[i - 1][0].first <= target && target <= dp[i - 1][0].second && a[0][i - 1] <= a[j][i])
output(i - 1, 0, target);
else
output(i - 1, 1, target);
cout << (j ? "B" : "A");
}
int main(){
ios::sync_with_stdio(false);
cin.tie(NULL);
cin >> n;
n *= 2;
for(int i = 1; i <= n; ++i) cin >> a[0][i];
for(int i = 1; i <= n; ++i) cin >> a[1][i];
dp[1][0] = {0, 0};
dp[1][1] = {1, 1};
for(int i = 2; i <= n; ++i)
for(int j = 0; j <= 1; ++j){
auto &ans = dp[i][j];
ans = {1, 0};
if(dp[i - 1][0] != pair{1, 0} && a[0][i - 1] <= a[j][i])
ans = merge(ans, dp[i - 1][0]);
if(dp[i - 1][1] != pair{1, 0} && a[1][i - 1] <= a[j][i])
ans = merge(ans, dp[i - 1][1]);
if(ans != pair{1, 0} && j){
ans.first++;
ans.second++;
}
//cout << ans.first << " " << ans.second << " - " << i << " " << j << endl;
}
if(dp[n][0].first <= n / 2 && n / 2 <= dp[n][0].second)
output(n, 0);
else if(dp[n][1].first <= n / 2 && n / 2 <= dp[n][1].second)
output(n, 1);
else
cout << "-1";
}
