#include <bits/stdc++.h>

using namespace std;

int main() {

    int n;
    bool B = false;
    bool two = false;

    cin >> n;

    vector<long long> c(n);

    for(int i = 0;i < n;i++){
        cin >> c[i];
    }

    for(int i = 0;i < n;i++){
        if(c[i] > 2) {
            B = true;
        }else if(c[i] == 2){
            two = true;
        }
    }

    if(two){
        if(c.size()%2 == 1) B = true;
    }else{
        if(c.size()%2 == 0) B = true;
    }

    if(B) cout << "B" << endl;
    else cout << "A" << endl;

    return 0;
}