#include <iostream>
#include <cmath>

using namespace std;

class ring{
public:
    void read(){
        cout << "x: ";
        cin >> x;
        cout << "y: ";
        cin >> y;
        cout << "R1: ";
        cin >> radius1;
        cout << "R2: ";
        cin >> radius2;
    }
    double getArea() const {
        return M_PI * (radius2 * radius2 - radius1 * radius1);
    }
    void printRing() const {
        cout << "Coordinates: (" << x << "; " << y << ")" << endl;
        cout << "R1: " << radius1 << endl;
        cout << "R2: " << radius2 << endl;
        cout << "Area:" << getArea() << endl;
    }
    void toCircle(){
        radius1 = 0;
    }
private:
    double x, y, radius1, radius2;
};

int main(){
    ring ring1;
    ring1.read();
    ring1.toCircle();
    ring1.printRing();
    return 0;
}