using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static long NN => long.Parse(ReadLine());
    static long[] NList => ReadLine().Split().Select(long.Parse).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var c = NList;
        var one = 0;
        var two = 0;
        for (var i = 0; i < n; ++i)
        {
            if (c[i] > 2)
            {
                WriteLine("B");
                return;
            }
            if (c[i] == 2) ++two;
            if (c[i] == 1) ++one;
        }
        if (two > 1) WriteLine("B");
        else WriteLine(one % 2 == 1 ? "A" : "B");
    }
}