using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Text;
using static System.Console;
using static System.Convert;
using static System.Math;
using static Extentions;

class IO
{
    int idx;
    string[] input;

    public IO(TextReader reader)
    {
        input = reader.ReadToEnd().Split(new[] { " ", Environment.NewLine },
            StringSplitOptions.RemoveEmptyEntries);
    }

    T Get<T>(Func<string, T> parser) => parser(input[idx++]);

    public string S => Get(s => s);
    public char C => Get(char.Parse);
    public int I => Get(int.Parse);
    public long L => Get(long.Parse);
    public double F => Get(double.Parse);
    public decimal D => Get(decimal.Parse);
    public BigInteger B => Get(BigInteger.Parse);

    T[] Gets<T>(int n, Func<string, T> parser)
        => input.Skip((idx += n) - n).Take(n).Select(parser).ToArray();

    public string[] Ss(int n) => Gets(n, s => s);
    public char[] Cs(int n) => Gets(n, char.Parse);
    public int[] Is(int n) => Gets(n, int.Parse);
    public long[] Ls(int n) => Gets(n, long.Parse);
    public double[] Fs(int n) => Gets(n, double.Parse);
    public decimal[] Ds(int n) => Gets(n, decimal.Parse);
    public BigInteger[] Bs(int n) => Gets(n, BigInteger.Parse);

    public void Write<T>(params T[] xs) => WriteLine(string.Join(" ", xs));
    public void Write(params object[] xs) => WriteLine(string.Join(" ", xs));
}

static class Extentions
{
}

static class Program
{
    public static void Main()
    {
#if !DEBUG
        SetOut(new StreamWriter(OpenStandardOutput()) { AutoFlush = false });
#endif
        Solve(new IO(In));
        Out.Flush();
    }

    static void Solve(IO io)
    {
        var n = io.I;
        var d = io.I;
        int na, nb, nc;

        for (nb = 0; ; nb++)
        {
            nc = nb - (d - n);
            na = n - nb - nc;
            if (na >= 0 && nc >= 0 && na + nb * 2 == d) break;
        }

        for (var i = 0; i < na; i++) Write('A');
        for (var i = 0; i < nb; i++) Write('B');
        for (var i = 0; i < nc; i++) Write('C');
    }
}