class Animal {
 
  public void signature(){
    System.out.println("I am an animal.");
  }
}

class Mammal extends Animal {
  int numberOfBabies;
  
  public Mammal(int babies) {
    numberOfBabies = babies;
  }
  
  public int getBabies() {
    return numberOfBabies;
  }
  
  public void signature() {
    System.out.println("I am a mammal! I birth "+numberOfBabies+" babies.");
  }
}

class Dog extends Mammal {
  private String name;
  
  public Dog(int babies, String name) {
    super(babies);
    this.name = name;
  }
  
  public String getName() {
    return name;
  }
  
  public void signature() {
    System.out.println("I am a dog! My name is "+name+".");
  }
}

public class Polymorphism {

  public static void main(String args[]) {
    Animal animal = new Animal(); // Animal reference and object
    Animal mammal = new Mammal(3);  // Animal reference but Mammal object
    Animal dog = new Dog(4, "Azor");    // Animal reference but Dog object

    animal.signature(); //output: I am an animal.
    mammal.signature(); //output: I am a mammal!
    dog.signature(); //output: I am a dog!
    
    //mammal.getBabies();
    //dog.getName();
  }
}