#include <bits/stdc++.h>
#define pb push_back
#define f first
#define sc second
using namespace std;
typedef long long int ll;
typedef string str;
const int inf = 1e9 + 9;
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
int n; cin >> n;
vector<int> a(2*n), b(2*n);
for(int &x: a) cin >> x;
for(int &x: b) cin >> x;
vector<vector<int>> dp(2*n, vector<int>(n+1, -1));
dp[0][0] = b[0];
dp[0][1] = a[0];
for(int i = 1; i < 2*n; i++){
for(int j = 0; j <= n; j++){
int x = inf;
if(dp[i-1][j] != -1 && b[i] >= dp[i-1][j]) x = min(x, b[i]);
if(j > 0 && dp[i-1][j-1] != -1 && a[i] >= dp[i-1][j-1]) x = min(x, a[i]);
dp[i][j] = (x == inf ? -1:x);
}
}
for(int i = 0; i < 2*n; i++){
for(int j = 0; j <= n; j++) cerr << dp[i][j] << " ";
cerr << "\n";
}
if(dp[2*n-1][n] == -1){
cout << "-1\n";
exit(0);
}
str ans = "";
int cur = n;
for(int i = 2*n-1; i > 0; i--){
if(dp[i][cur] >= dp[i-1][cur] && dp[i-1][cur] != -1) ans+="B";
else{
ans+="A";
cur--;
}
}
ans+=(cur == 1 ? "A":"B");
reverse(ans.begin(), ans.end());
cout << ans << "\n";
}
