#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    int N; cin >> N;
    int c1 = 0, c2 = 0, co = 0;
    rep(i,N){
        int c; cin >> c;
        if(c == 1) c1++;
        else if(c == 2) c2++;
        else if(c != 0) co++;
    }

    int A = (c1 % 2 == 1 && c2 == 0 && co == 0) || (c1 % 2 == 1 && c2 == 1 && co == 0);
    cout << (A ? "A" : "B") << endl;
}