#include <iostream>
#include <cmath>
#include <vector>

template<typename T, typename M>
struct Pair{
	T first;
	M second;
	Pair() = default;
	Pair(T a, T b): first(a), second(b){}
};

template<typename T, typename M>
inline std::ostream& operator<<(std::ostream& os, const Pair<T,M>& obj){ return os <<"x : "<< obj.first << " y : "<< obj.second; }
template<typename T, typename M>
inline std::istream& operator>>(std::istream& is, Pair<T,M>& obj){ return is >> obj.first >> obj.second; }

class Shape{
public:
    // virtual ~Shape() = default;
	virtual double area() const = 0;
	virtual Pair<double, double> center() const = 0;
	friend inline std::ostream& operator<<(std::ostream& os, const Shape& obj) { return obj.output(os); }
	friend inline std::istream& operator>>(std::istream& is, Shape& obj){ return obj.input(is); }

protected:
	virtual std::istream& input(std::istream& is) = 0;
	virtual std::ostream& output(std::ostream& os) const = 0;
	double edge_length(const Pair<double, double>& a, const Pair<double, double>& b) const { return std::sqrt(std::pow(b.first - a.first, 2) + std::pow(b.second - a.second, 2));}
	Pair<double, double> edge_center(const Pair<double, double>& a, const Pair<double, double>& b) const { return Pair<double, double>((a.first + b.first)/2, (a.second + b.second)/2);}
};

class Quadrangle: public Shape{
public:
	// friend Square;
	double area() const {} // можно определить для общего случая четырехугольника
	Pair<double, double> center() const {} // можно определить для общего случая четырехугольника

protected:
	std::istream& input(std::istream& is) { return is >> a[0] >> a[1] >> a[2] >> a[3]; }
	std::ostream& output(std::ostream& os) const{ return os << a[0] << "   " << a[1] << "   " << a[2] << "   " << a[3] << "\n"; }
	Pair<double,double> a[4];

};

class Rhombus:public Quadrangle{
public:
	// Rhombus() = default;
	double area() const { return (edge_length(a[0], a[2]) * edge_length(a[1], a[3]))/2; }
	Pair<double, double> center() const { return edge_center(a[0], a[2]); }
};

class Square: public Rhombus{
public:
	double area() const { return std::pow(edge_length(a[0], a[1]), 2); }
};

class Trapezoid:public Quadrangle{
public:
	double area() const {} //а тут нужно написать как вычислеть площадь и центр
	Pair<double, double> center() const {}
};

double sum(std::vector<Shape*> v){
	double res= 0;
	for (auto i = v.begin(); i!= v.end(); ++i){
		res += (*i)->area();
	}
	return res;
}

void remove_elem(int index, std::vector<Shape*>& v){
	v.erase(v.begin() + index);
}

void print(std::vector<Shape*>& v){
	for (auto i = v.begin(); i!= v.end(); ++i){
		std::cout << (**i) << (*i)->center()<< " " << (*i)->area()<< "\n";
	}
}

int main(){
	std::vector<Shape*> v;

	Rhombus* r1 = new Rhombus(), *r2 = new Rhombus();
	Square* s1 = new Square(), *s2 = new Square();
	std::cin >> (*r1) >> (*r2) >> (*s1) >> (*s2);
	v.push_back(r1);
	v.push_back(r2);
	v.push_back(s1);
	v.push_back(s2);

	print(v);

	std::cout << sum(v)<< "\n";

	remove_elem(1, v);

	print(v);

	return 0;
}

/*
2
4
-3
7
-6
6
-1
3
2
4
-3
7
-6
6
-1
3
2
4
-3
7
-6
6
-1
3
2
4
-3
7
-6
6
-1
3
*/