using System;

public class Hello
{
    static void Main()
    {
        var n = int.Parse(Console.ReadLine().Trim());
        string[] line = Console.ReadLine().Trim().Split(' ');
        var a = Array.ConvertAll(line, int.Parse);
        getAns(n, a);
    }
    static void getAns(int n, int[] a)
    {
        var c1 = 0;
        var c2 = 0;
        for (int i = 0; i < n; i++)
        {
            if (a[i] == 0) continue;
            else if (a[i] == 1) c1++;
            else if (a[i] == 2)
            {
                c2++;
                if (c2 >= 2) { Console.WriteLine("B"); return; }
            }
            else { Console.WriteLine("B"); return; }
        }
        Console.WriteLine((c2 == 0 && c1 % 2 == 1) | (c2 == 1 && c1 % 2 == 1) ? "A" : "B");
    }
}