#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());
    int cnt1 = 0, cnt2 = 0;
    for (int i = 0; i < N; i++)
    {
        if (C[i] == 1)
            cnt1++;
        else if (C[i] == 2 && cnt2 < 1)
            cnt2++;
        else
        {
            cout << 'B' << endl;
            return 0;
        }
    }
    cout << (cnt1 % 2 == 1 || (cnt1 % 2 == 1 && cnt2 == 1) ? 'A' : 'B') << endl;
}