using System;

public class Test
{
	class Animal
	{
		
	}
	
	class Dog : Animal
	{
		public virtual void woof() { }
	}
	
	class Cat : Animal
	{
		public virtual void meow() { }
	}
	
	public static void Main()
	{
		var cat = new Cat();
		var dog = (Dog)cat;
		var dog2 = cat as Dog;
	}
}