using System;

using System.Globalization;

using System.Numerics;

using System.Text;

​

public class Program

{

    public static void Main()

    {

        var guid = "e7eaf8ed-86f8-53e4-8a9d-ba62d95df565";

        guid = "0" + guid.Replace("-", "");

        var bigInt = BigInteger.Parse(guid, NumberStyles.HexNumber);

        var base36 = bigInt.ToBase36();

        Console.WriteLine(base36.ToString());

    }

}

​

 public static class NumberExtensions

 {

     private const string Base36Chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

​

     public static string ToBase36(this BigInteger value)

     {

         // Handle the special case where the value is 0

         if (value == 0)

             return "0";

​

         var result = new StringBuilder();

​

         // While the value is greater than 0, divide by 36 and prepend the corresponding character

         while (value > 0)

         {

             int remainder = (int)(value % 36);

             var base36Char = Base36Chars[remainder];

             result.Insert(0, base36Char);

             value /= 36;

         }

​

         return result.ToString();

     }

 }