#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
using namespace std;

int main()
{
	int N; cin >> N;
	vector<int>C(N);
	int cnt1 = 0, cnt2 = 0;
	for (int i = 0; i < N; i++) {
		cin >> C[i];
		if (C[i] > 2)cnt2 += 1000;
		else if (C[i] > 1)cnt2++;
		else if (C[i] == 1)cnt1++;
	}

	if (cnt2 > 1)cout << "B" << endl;
	else {
		if (cnt1 % 2)cout << "A" << endl;
		else cout << "B" << endl;
	}

    return 0;
}