using System;

using System.Linq;

using System.IO;

using System.Collections.Generic;

public class Program

{

    public static string IntToLetters(int value)

    {

        string result = string.Empty;

        while (value >= 0)

        {

            result = (char)('A' + value % 26) + result;

            value /= 26;

            value--;

        }

        return result;

    }

    public static void Main()

    {

        Console.WriteLine(IntToLetters(0));

        Console.WriteLine(IntToLetters(25));

        Console.WriteLine(IntToLetters(26));

        Console.WriteLine(IntToLetters(27));

        Console.WriteLine(IntToLetters(42));

    }

}