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

}