import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int N = scan.nextInt();
		boolean flag = false;
		int cnt1 = 0;
		int cnt2 = 0;
		for(int i = 0; i < N; i++) {
			int C = scan.nextInt();
			if(C > 2){
				flag = true;
			}
			if(C == 1) {
				cnt1++;
			}
			if(C == 2) {
				cnt2++;
			}
		}
		scan.close();
		if(flag) {
			System.out.println("B");
		}else {
			if(cnt1 == N && cnt1 % 2 == 1) {
				System.out.println("A");
			}else if(cnt2 == 1 && cnt1 % 2 == 1) {
				System.out.println("A");
			}else {
				System.out.println("B");
			}
		}
	}
}