#include <iostream>
#include <algorithm>
using namespace std;

int main(){
    int N;
    cin >> N;
    int candies[N];
    int zero_box = 0;
    for(int i = 0; i < N; i++){
        cin >> candies[i];
        if(!candies[i]){
            zero_box++;
        }
    }
    sort(candies, candies + N, greater<int>());
    if((N - zero_box) % 2 == 1){
        for(int i = 0; i < N - zero_box; i++){
            if(candies[i] != 1){
                cout << "B" << endl;
                return 0;
            }
        }
    }else{
        if(candies[0] != 2){
            cout << "B" << endl;
            return 0;
        }
        for(int i = 1; i < N - zero_box; i++){
            if(candies[i] != 1){
                cout << "B" << endl;
                return 0;
            }
        }
    }
    if(N == zero_box){
        cout << "B" << endl;
    }else{
        cout << "A" << endl;
    }
}