import java.util.*;
import java.lang.*;
import java.io.*;

class Ideone
{
	interface Animal {
		public void eat();
	}
	
	interface Dog extends Animal {
		public void woof();
	}
	
	interface Cat extends Animal {
		void meow();
	}
	
	static class Poppy implements Dog {
		public void eat() {}
		public void woof() {}
	}
	
	static class Dazy implements Cat {
		public void eat() {}
		public void meow() {}
	}
	
	static void replace(Animal animal) {
		animal = new Poppy();
	}
	
	public static void main (String[] args) throws java.lang.Exception
	{
		Cat cat = new Dazy();
		replace(cat);
		cat.meow();
	}
}