interface shape2D{
	double PI=3.14159;
	abstract double area();
}
interface shape3D extends shape2D{
      double volume(); 
}
class Circle implements shape3D{
	double radius;
	public Circle(double r)	{
	   radius=r;
	}
	public double area(){                        //ʵּӸӿڵķ
		return PI*radius*radius;
	}
	public double volume(){                 //ʵֱӸӿڵķ
		return 4*PI*radius*radius*radius/3;
	}
}
public class InterfaceDemo2{
	public static void main(String args[]){
	   Circle cir=new Circle(15);
	   System.out.println("Circle area="+cir.area());
	   System.out.println("Circle vloume="+cir.volume());
	}
}