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

template <typename T>
T gcd(T x, T y)
{
    if (y == 0)
        return x;
    return gcd(y, x % y);
}

template <typename T>
T lcm(T x, T y)
{
    if (x == 0 || y == 0)
        return 0;
    return x / gcd(x, y) * y;
}

int main()
{
    int N;
    cin >> N;
    vector<long> C(N);
    for (int i = 0; i < N; i++)
    {
        cin >> C[i];
    }
    sort(C.begin(), C.end(), ::greater<int>());
    bool flag = false;
    for (int i = 0; i < N; i++)
    {
        if (C[i] == 0)
            continue;
        if (C[i] == 1)
            flag = !flag;
        else
            flag = true;
    }
    cout << (flag ? 'B' : 'A') << endl;
}