interface Drawable {
  void draw(); // implicitly public and abstract
}

class Circle implements Drawable {
  @Override
  public void draw() {
    System.out.println("Drawing a circle");
  }
}

class Square implements Drawable {
  @Override
  public void draw() {
    System.out.println("Drawing a square");
  }
}

public class Main {
  public static void main(String[] args) {
    Drawable shape = new Circle();
    shape.draw(); // Drawing a circle
  }
}