ExtendsAnimal

public abstract class Animal {

	void run() {
		System.out.println("달려간다.");
	}

	abstract void sound();
}

class Dog extends Animal {

	@Override
	void sound() {
		System.out.println("멍멍");
	}

}

class Suricata extends Animal {

	@Override
	void sound() {
		System.out.println("꾸르륵");
	}
}

class Duck extends Animal {

	@Override
	void sound() {
		System.out.println("꽥");
	}

}