using System;

​

public class Program

{

    public class Parent

    {

        public string item{get;set;}

    }

​

    public class Child : Parent

    {

    }

​

    public static void ConsoleWrite(Parent pitem)

    {

        Console.Write(pitem.item);

    }

​

    public static void Main()

    {

        ConsoleWrite(new Child(){item = "foo"});

    }

}