interface Shape 
{
    void calculateArea();
}

class Rectangle implements Shape 
{
    float length,width;

    Rectangle(float l, float w) 
	{
        length = l;
        width = w;
    }

    public void calculateArea() 
	{
        float a=length * width;
		System.out.println("Area of Rectangle: " + a);
    }
}

class Circle implements Shape 
{
    float radius;

    Circle(float r) 
	{
        radius = r;
    }

    public void calculateArea() 
	{
        float a= 3.14f * radius * radius;
		System.out.println("Area of Circle: " + a);
    }
}

public class InterfaceDemo 
{
    public static void main(String[] args) 
	{
        Rectangle rectangle = new Rectangle(10.0f, 5.0f);
        Circle circle = new Circle(7.0f);
		rectangle.calculateArea();
		circle.calculateArea();
    }
}