public abstract class Shape implements Comparable<Shape>{
   private String name;
   
   public Shape(String name) {
      this.name = name;
   }

   public abstract double area();
   
   public final String toString() {
      return name +" of area " + area();
   }
   
   public final int compareTo(Shape other) {
      double difference = area() - other.area();
      if (difference < 0)
         return -1;
      else if (difference == 0)
         return 0;
      else // difference > 0
         return 1;
   }


}