using System;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using System.Text;

public class Program

{

    public static void Main()

    {

       string base64Input = "UHJhbW9kIEFkaHVkZQ==";

        string base64WithIso = "UHLCbW9kIMBkaHVkZQ==";

        string base64WithASCII = "UHJtb2QgZGh1ZGU=";

         Console.WriteLine(Program.Decode(base64Input));

         Console.WriteLine(Program.Decode(base64WithIso,"ISO-8859-1"));

         Console.WriteLine(Program.Decode(base64WithIso,"ISO-8859-1"));

         Console.WriteLine(Program.Decode(base64WithIso,"ISO-8859-1"));

         Console.WriteLine(Program.Decode(base64WithIso,"ISO-8859-1"));

         Console.WriteLine(Program.Decode(base64WithIso,"ISO-8859-1"));

        GetEncodings();

    }

    public static void GetEncodings()

    {

        foreach( EncodingInfo ei in Encoding.GetEncodings() )  {

         Console.WriteLine("\""+ei.Name+"\",");

        }

    }

    public static string Decode(string input,string encoding="")

    {

        string result=string.Empty;

        if(!string.IsNullOrEmpty(encoding))

        {

        var encodingType=Encoding.GetEncoding(encoding);

        result=encodingType.GetString(Convert.FromBase64String(input));

        }else

        {

        result=Encoding.UTF8.GetString(Convert.FromBase64String(input));

        }

        return result;

    }

}