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

int main() {
	int i, n, a, one, two, flag = 1;
	one = two = 0;
	cin >> n;
	for (i = 0; i < n; i++) {
		cin >> a;

		if (a == 1)one++;
		else if (a == 2) {
			if (two ==1)two = 1;
			else { flag = 0; break; two++;}
		}
	
		else if (a > 2)flag = 0;
		if ((two>1) || flag == 0) {
			flag = 0;
			break;
		}
	}

	if (flag == 1) {
		if (two == 0)if (one % 2 == 0)flag = 0;//2以上の数があるとき
		else if (two == 1)if (one % 2 == 0)flag = 0;
	}
	if (flag == 0)cout << "B" << endl;
	else cout << "A" << endl;
	return 0;
}