using System;

namespace Playground
{
    class Program
    {
        static char[] collector = new char[0];

        static void Main()
        {
            int limit = 0;

            Console.Write("How many letters deep? ");
            int.TryParse(Console.ReadLine(), out limit);

            Challenge(limit);
        }

        static char IncrementChar(ref char character)
        {
            character++;

            if (character > '9' && character < 'a')
            {
                character = 'a';
            }
            else if (character > 'z')
            {
                character = '0';
            }

            return character;
        }

        static void Challenge(int limit)
        {
            char currentChar = (char) ('0' - 1);

            for (int i = 0; i < limit; i++)
            {
                for (int j = 0; j < Math.Pow(36, collector.Length); j++)
                {
                    for (int k = 0; k < 36; k++)
                    {
                        foreach (char letter in collector)
                        {
                            Console.Write(letter);
                        }

                        Console.WriteLine(IncrementChar(ref currentChar));
                    }

                    if (i > 0)
                    {
                        for (int k = 1;
                            IncrementChar(ref collector[collector.Length - k]) == '0' && k < collector.Length;
                            k++) ;
                    }
                }

                char[] temp = collector;
                collector = new char[collector.Length + 1];

                for (int j = 0; j < temp.Length; j++)
                {
                    collector[j] = temp[j];
                }

                collector[collector.Length - 1] = '0';
            }
        }
    }
}