import java.util.Arrays;
import java.util.LinkedList;
import java.util.Scanner;

public class Main {
	
	public static long MOD = 1000000007;
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		final int N = sc.nextInt();
		int win = 0;
		for(int i = 0; i < N; i++){
			final int c = sc.nextInt();
			
			if(c == 1){
				win++;
			}
		}
		
		System.out.println(win % 2 == 1 ? "A" : "B");
	}
}