import java.io.*;
import java.util.*;


public class Main_yukicoder582 {

	private static Scanner sc;
	private static Printer pr;

	private static void solve() {
		int n = sc.nextInt();

		int[] c = new int[n];
		int cnt = 0;
		int sum = 0;
		int cnt1 = 0;
		int cnt2 = 0;
		for (int i = 0; i < n; i++) {
			c[i] = sc.nextInt();

			if (c[i] > 0) {
				cnt++;
			}
			sum += c[i];
			if (c[i] == 1) {
				cnt1++;
			}
			if (c[i] == 2) {
				cnt2++;
			}
		}

		if (cnt == 1) {
			if (sum == 1) {
				pr.println('A');
			} else {
				pr.println('B');
			}
		} else {
			if (cnt1 == cnt) {
				if (cnt % 2 == 0) {
					pr.println('B');
				} else {
					pr.println('A');
				}
			} else if (cnt2 == 1 && cnt2 + cnt1 == cnt) {
				if (cnt1 % 2 == 0) {
					pr.println('B');
				} else {
					pr.println('A');
				}
			} else {
				pr.println('B');
			}
		}
	}

	// ---------------------------------------------------
	public static void main(String[] args) {
		sc = new Scanner(System.in);
		pr = new Printer(System.out);

		solve();

		pr.close();
		sc.close();
	}

	private static class Printer extends PrintWriter {
		Printer(PrintStream out) {
			super(out);
		}
	}
}