using System;

public class BaseClass

{

    public virtual int PropertyA { get; private set; }

}

​

public class DerivedClass : BaseClass

{

    //private int _propertyA;

    //public override int PropertyA

    //{

    //    get {

    //        return _propertyA;

    //    }

    //}

​

    public override int PropertyA { get; }

}

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        var instance = new DerivedClass();

        Console.WriteLine(instance.PropertyA);

    }

}