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

int main() {
	int n;
	cin >> n;
	int64_t a[n];
	for (auto &i : a) {
		cin >> i;
	}
	bool f = (accumulate(a, a + n, 0ll) == n + 1 && count(a, a + n, 2) == 1) || (accumulate(a, a + n, 0ll) == 1);
	cout << "BA"[f] << endl;
	return 0;
}