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


int main(){
	int n,a,cnt=0,cnt2=0;
	cin >> n;
	for(int i=0;i<n;i++){
		cin >> a;
		if(a==1) cnt++;
		else if(a==2) cnt2++;
		else{
			cout << "B" << endl;
			return 0;
		}
	}
	
	if(cnt2==0&&cnt%2 || cnt2==1&&cnt%2) cout << "A" << endl;
	else cout << "B" << endl;
	return 0;
}