import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int[] c = new int[n];
		for(int i = 0 ; i < n ; i++) {
			c[i] = sc.nextInt();
		}
		int odd = 0, even = 0;
		for(int i = 0 ; i < n ; i++) {
			if(c[i] >= 3) {
				System.out.println("B");
				return;
			}
			if(c[i] == 0) even++;
			else if(c[i] == 1) odd++;
		}
		if(odd % 2 == 1 && even == 0 || odd % 2 == 0 && even == 1) {
			System.out.println("A");
		} else {
			System.out.println("B");
		}
 	}
}