using System;

public class Program

{

    public static void Main()

    {

        var x = new MyClass("ok");

    }

}

​

​

public abstract class PrivateConstructor{

    protected PrivateConstructor(){

        Console.WriteLine("PrivateConstructor ctor");

    }

}

​

public class MyClass: PrivateConstructor

{

    public MyClass(string choto)

    {

        Console.WriteLine("MyClass ctor " + choto);

    }

}

​