#include <iostream>
using namespace std;

class Shape {
public:
 virtual void area() = 0;
};


class Circle : public Shape {
private:
 double radius;

public:
 Circle(double r): radius(r){}

 void area() {
     cout << "Circle area: "<< 3.14 * radius * radius << endl;
 }
};


class Rectangle : public Shape {
private:
 double length;
 double width;

public:
 Rectangle(double l, double w): length(l), width(w) {}

 void area() {
 cout << "Rectangle area: " << length * width << endl;
 }
};


int main() {
    Circle circle(5);
    Rectangle rectangle(4, 6);
   
   circle.area();
   rectangle.area();
   
 return 0;
}