using System;

​

public class Human

{

    public void Child(string name, int? child)

        {

            Console.WriteLine("{0} has {1} child",name,child);

        }

}

public class Program

{

    public static void Main()

    {

        Human h = new Human();

        int? child = null;

        h.Child("miha",4);

        h.Child("mika",0);

        h.Child("mika",null);

    }

}