#include <iostream>
#include <cstdlib>
#include "cmath"
#include <vector>

using namespace std;
class Line;
class Shape;
class Triangle;
class Quadrangle;
class Point{
private:
    double x;
    double y;

public:
    Point(double x, double y){
        this->x = x;
        this->y = y;
    }

    double getX(){
        return this->x;
    }

    double getY(){
        return this->y;
    }

    double getDistance(Point *punkt){

        return sqrt(pow((punkt->getX() - this->getX()), 2) + pow((punkt->getY() - this->getY()), 2));

    }
};

class Line{
private:
    Point* A;
    Point* B;
public:
    Line(Point *A, Point *B){
        this->A = A;
        this->B = B;
    }

    double getA(){

        return  (this->B->getY() - this->A->getY())/(this->B->getX() - this->A->getX());

    }

    double getB(){
        double y = (this->A->getY() - (this->A->getY() - this->B->getY())/(this->A->getX() - this->B->getX()) * this->A->getX());

        return y;
    }


    double getLength(){

        return sqrt(pow((this->B->getX() - this->A->getX()), 2) + pow((this->B->getY() - this->A->getY()), 2));
    }



};

class Shape{
protected:
    vector<Point*> punkty;
public:
    Shape(){
    };

    virtual double getArea()=0;

    void addPoint(Point *punkt){
        this->punkty.push_back(punkt);
    }

    Point *getPoint(int i){
        return this->punkty[i];
    }

    double getCircumference(){
        double obw = 0;

        for(int i = 0; i < punkty.size(); i++){
            if(i == punkty.size() - 1){
                obw += getPoint(i)->getDistance(getPoint(0));
            }else {
                obw += getPoint(i)->getDistance(getPoint(i+1));
            }

        }
        return obw;
    }



};

class Triangle : public Shape{
public:
    Triangle(Point *punktA, Point *punktB, Point *punktC){
        addPoint(punktA);
        addPoint(punktB);
        addPoint(punktC);
    }

    double getArea(){


        double a = getPoint(0)->getDistance(getPoint(1));
        double b = getPoint(1)->getDistance(getPoint(2));
        double c = getPoint(2)->getDistance(getPoint(0));

        double p = 0.5*(a+b+c);

        return sqrt(p *(p-a)*(p-b)*(p-c));
    }
};

class Quadrangle : public Shape{
public:
    Quadrangle(Point *punktA, Point *punktB, Point *punktC, Point *punktD){
        addPoint(punktA);
        addPoint(punktB);
        addPoint(punktC);
        addPoint(punktD);
    }

    double getArea() {
        Triangle *trojkat1 = new Triangle(getPoint(0),getPoint(1),getPoint(2));
        Triangle *trojkat2 = new Triangle(getPoint(3), getPoint(0), getPoint(2));

        return trojkat1->getArea() + trojkat2->getArea();
    }


};







int main() {

    return 0;
}