#include <bits/stdc++.h>

using namespace std;

int main(void)
{
    cin.tie(0);
    ios::sync_with_stdio(false);

    vector<int> v;
    int n,x;
    long long int sum = 0;

    cin >> n;

    for(int i=0;i<n;i++)
    {
        cin >> x;
        if (x > 0) v.push_back(x);
        sum += x;
    }
    sort(v.begin(), v.end());

    if (sum == 0)
    {
        cout << "B" << '\n';
    }
    if (v.back() == 1) 
    {
        if (sum % 2 == 0) 
        {
            cout << "B" << '\n';
        }
        else
        {
            cout << "A" << '\n';
        }
    }

    map<int, int> cnt;
    for(auto x : v) cnt[x] += 1;

    if (cnt[2] == 1 and v.size() == (cnt[1] + cnt[2]) and cnt[1] % 2 == 1) 
    {
        cout << "A" << '\n';
    }
    else
    {
        cout << "B" << '\n';
    }
    return 0;   
}