using System;

public class Program

{

    public static void Main()

    {

        Cat cat = new BigCat();

        //BigCat cat = new BigCat();

        cat.DoCat();

        cat.V_DoCat();

    }

}

​

public class Cat

{

    public void DoCat()

    {

       Console.WriteLine("50");

    }

​

    public virtual void V_DoCat()

    {

       Console.WriteLine("5020");

    }

}

​

public class BigCat : Cat

{

    public new void DoCat()

    {

        base.DoCat();

        Console.WriteLine("500");

    }

​

    public override void V_DoCat()

    {

        Console.WriteLine("50200");

    }

}