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

int main() {
	int n;
	cin >> n;
	int64_t a[n];
	for (auto &i : a) {
		cin >> i;
		if (3 <= i) {
			cout << 'B' << endl;
			return 0;
		}
	}
	int one = count(a, a + n, 1), two = count(a, a + n, 2);
	cout << "BA"[(one & 1) && (two == 1)] << endl;
	return 0;
}