#include <iostream>
#include <stdio.h>
#include <cstring>
#include <math.h>
#include <algorithm>
#include <vector>
#include <string>
#include <stdlib.h>
#include <queue>
#include <stack>
#include <utility>
#define rep(i,n) for(int i=0;i<n;i++)
#define rrep(i,n) for(int i=n-1;i>=0;i--)
#define FOR(i,a,b) for(int i=a;i<b;i++)
#define ll long long
#define INF 1000000001
#define mod 1000000007
using namespace std;

int main(){
	//cin.tie(0);
	//ios::sync_with_stdio(false);
	

	int n;
	cin>>n;
	vector<int> c(n);
	int c2=0;
	int c1=0;
	rep(i,n){
		cin>>c[i];
		if(c[i]>2){
			cout<<"B"<<endl;
			return 0;
		}
		if(c[i]==2){
			c2++;
		}
		if(c[i]==1){
			c1++;
		}
	}
	if(c2>1){
		cout<<"B"<<endl;
		return 0;
	}
	else if(c1%2==0){
		cout<<"B"<<endl;
	}else{
		cout<<"A"<<endl;
	}
}