using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Contest
{
    class Scanner
    {
        private string[] line = new string[0];
        private int index = 0;
        public string Next()
        {
            if (line.Length <= index)
            {
                line = Console.ReadLine().Split(' ');
                index = 0;
            }
            var res = line[index];
            index++;
            return res;
        }
        public int NextInt()
        {
            return int.Parse(Next());
        }
        public long NextLong()
        {
            return long.Parse(Next());
        }
        public string[] Array()
        {
            line = Console.ReadLine().Split(' ');
            index = line.Length;
            return line;
        }
        public int[] IntArray()
        {
            return Array().Select(int.Parse).ToArray();
        }
        public long[] LongArray()
        {
            return Array().Select(long.Parse).ToArray();
        }
    }

    class Program
    {
        private int N;
        private int[] C;
        private void Scan()
        {
            var sc = new Scanner();
            N = sc.NextInt();
            C = sc.IntArray();
        }

        public void Solve()
        {
            Scan();
            int one = 0;
            int two = 0;
            foreach (int i in C)
            {
                switch (i)
                {
                    case 0:
                        break;
                    case 1:
                        one++;
                        break;
                    case 2:
                        two++;
                        break;
                    default:
                        Console.WriteLine("B");
                        return;

                }
            }
            switch (two)
            {
                case 0:
                    Console.WriteLine(one % 2 == 1 ? "A" : "B");
                    return;
                case 1:
                    Console.WriteLine(one % 2 == 1 ? "A" : "B");
                    return;
                default:
                    Console.WriteLine("B");
                    return;
            }
        }


        static void Main(string[] args)
        {
            new Program().Solve();
        }
    }
}