using System;

public class Program

{

    public static void Main()

    {

        byte[] test = new byte[4];

        test[0] = 0;

        test[1] = 1;

        test[2] = 2;

        test[3] = 3;

        foo(test);

        Console.WriteLine(test[0]);

        Console.WriteLine(test[1]);

        Console.WriteLine(test[2]);

        Console.WriteLine(test[3]);

    }

    private static void foo(byte[] arg) {

        byte temp = arg[0];

        arg[0] = arg[3];

        arg[3] = temp;

    }

}