#include <iostream>
#include <vector>
#include <utility>
#include <algorithm>
#include <string>
#include <stack>
using ll = long long;
#define MOD 1000000007
using namespace std;

int main(){
    int N;
    cin >> N;
    int x[4] = {0};
    for(int i = 0; i < N; i++)
    {
        int c;
        cin >> c;
        switch (c) {
            case 0:
                x[0]++; break;
            case 1:
                x[1]++; break;
            case 2:
                x[2]++; break;
            default:
                x[3]++; break;
        }
    }
    if (x[1] % 2 == 1 && x[2] <= 1 && x[3] == 0) {
        cout << "A" << endl;
    }
    else {
        cout << "B" << endl;
    }
    return 0;
}