using System;
using System.Linq;

namespace StudyApp
{
    class Program
    {
        static void Main(string[] args)
        {
            const char zero = 'C';
            const char one = 'A';
            const char two = 'B';

            var inputs = Console.ReadLine().Trim().Split(' ').Select(data => int.Parse(data)).ToArray();
            var n = inputs[0];
            var d = inputs[1];

            var result = new char[n];
            var diff = d - n;

            for (int i = 0; i < n; i++)
            {
                if (diff > 0)
                {
                    result[i] = 'B';
                    diff--;
                }
                else if (diff < 0)
                {
                    result[i] = 'C';
                    diff++;
                }
                else
                {
                    result[i] = 'A';
                }
            }
            foreach (var data in result.OrderBy(data => data))
                Console.Write(data);
            Console.Write("\n");
        }
    }
}