using System;

using System.Text;

using System.Globalization;

public class Program

{

    public static void Main()

    {

      var str = "596d6c304c6d78354c7a4a3262585a455a6a514b";

      var hexBytes = new byte[str.Length/2];

      for (int x = 0; x < str.Length / 2; x++)

      {

        var hexByteString = str.Substring(x*2, 2);

        hexBytes[x] = byte.Parse(hexByteString, NumberStyles.HexNumber);

      }

      var concatenatedString = string.Concat(Encoding.UTF8.GetChars(hexBytes));

      Console.WriteLine(concatenatedString);

      var base64Bytes = Convert.FromBase64String(concatenatedString);

      var decodedString = string.Concat(Encoding.UTF8.GetChars(base64Bytes));

      Console.WriteLine(decodedString);

    }

}