using System;

​

public class Program

{

    public static void Main()

    {

        var myObject = new DerivedClass();

        BaseClass myObjectBase = myObject;

        Console.WriteLine(myObject.GimmeFive());

        Console.WriteLine(myObjectBase.GimmeFive());

        Console.WriteLine();

        Console.WriteLine(myObject.GimmeNine());

        Console.WriteLine(myObjectBase.GimmeNine());

    }

}

​

public class BaseClass

{

    public string GimmeFive()

    {

        return "base-5";

    }

​

    public virtual string GimmeNine()

    {

        return "base-9";

    }

}

​

public class DerivedClass : BaseClass

{

    public string GimmeFive()

    {

        return "derived-5";

    }

​

    public override string GimmeNine()

    {

        return "derived-9";

    }

}