using System;

using System.Text;

public class Program

{

    public static void Main()

    {

        string inputString = "Räksmörgås";

        string asAscii = Encoding.ASCII.GetString(

            Encoding.Convert(

                Encoding.UTF8,

                Encoding.GetEncoding(

                    Encoding.ASCII.EncodingName,

                    new EncoderReplacementFallback(string.Empty),

                    new DecoderExceptionFallback()

                    ),

                Encoding.UTF8.GetBytes(inputString)

            )

        );

        Console.WriteLine(asAscii);

    }

}