using System;

public class Program

{

    public static void Main()

    {

        new Derived("param");

    }

}

​

public class Base

{

    public Base()

    {

        Console.WriteLine("Base.Base()");

    }

}

​

public class Derived : Base

{

    public Derived() : base()

    {

        Console.WriteLine("Derived.Derived()");

    }

    public Derived(object param) : base()

    {

        Console.WriteLine("Derived.Derived(object param)");

    }

​

}