#include <iostream>
#define REP(i,a,b) for(int i=(a);i<(b);i++)
#define RREP(i,a,b) for(int i=(a);i>=(b);i--)
using namespace std;
int n,a;

int main(){
	cin >> n;
	int t=0,o=0;
	REP(i,0,n){
		cin >> a;
		if(a>2){cout << 'B' << endl; return 0;}
		else if(a==2) t++;
		else o++;
	}
	
	if(t>1) cout << 'B' << endl;
	else cout << (o%2?'A':'B') << endl;
	
	return 0;
}