#include <bits/stdc++.h>
using namespace std;

vector<int> delete_zeros(const vector<int> & Cs){
    vector<int> cs;
    for (auto & c : Cs) if (c != 0) cs.push_back(c);
    return cs;
}

bool is_all_ones(const vector<int> & cs){
    for (auto & c : cs) if (c != 1) return false;
    return true;
}

bool is_all_ones_but_two(const vector<int> & cs){
    int count_two = 0;
    for (auto c : cs){
        if (c == 2){
            ++count_two;
        }else if (c != 1){
            return false;
        }
    }
    if (count_two != 1){
        return false;
    }else{
        return true;
    }
}

bool first_wins(int N, const vector<int> & Cs){
    auto cs = delete_zeros(Cs);
    if (is_all_ones(cs)){
        return ((cs.size() & 1) == 1);
    }else if (is_all_ones_but_two(cs)){
        return ((cs.size() & 1) == 0);
    }else{
        return false;
    }
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int N;
    cin >> N;
    vector<int> Cs(N);
    for (auto & c :Cs) cin >> c;
    if (first_wins(N, Cs)){
        cout << 'A' << endl;
    }else{
        cout << 'B' << endl;
    }
    return 0;
}