using System;

public class Program

{

    public static void Main()

    {

        int d = 0;

        Foo(1, 2, d = 3);

        Console.WriteLine("d is now {0}", d);

    }

    public static void Foo(int a, int b, int c = 0, int d = 0)

    {

        Console.WriteLine("a = {0}, b = {1}, c = {2}, c = {3}", a, b, c, d);    

    }

}