using System;

using System.Text;

using System.Linq;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(EncodeShortLink(1679616));    

        Console.WriteLine(EncodeShortLink(59796171));

​

    }

        public static readonly string Alphabet = "abcdefghijklmnopqrstuvwxyz0123456789";

        public static readonly long Base = Alphabet.Length;

​

        public static string EncodeShortLink(long index)

        {

​

            if (index == 0) return Alphabet[0].ToString();

​

            var s = new StringBuilder();

​

            while (index > 0)

            {

                s.Append(Alphabet[Convert.ToInt32(index % Base)]);

                index = index / Base;

            }

​

            return string.Join(string.Empty, s.ToString().Reverse());

​

        }

}