#include<iostream>
#include<cstdlib>
#include<cmath>

using namespace std;

int main()
{
	double a, b, h;
	int ops;

	cout << "0 - prostokat\n1 - kolo\n2 - trojkat\n3 - trapez\n";
	cin >> ops;

	switch(ops)
	{
		case 0:
		{
			cout << "Podaj a, b\n";
			cin >> a;
			cin >> b;
			cout << "pole prostokata wynosi " << a * b << endl;
		} break;
	case 1:
		{
			cout << "podaj promien\n";
			cin >> a;
			cout << "Pole kola wynosi " << a * a * M_PI;

		} break;
	case 2:
		{
			cout << "Podaj podstawe i wysokosc\n";
			cin >> a;
			cin >> h;
			cout << "Pole trojkata wynosi " << a * h / 2 << endl;

		} break;
	case 3:
		{
			cout << "Podaj podstawy trapezu oraz wysokosc\n";
			cin >> a;
			cin >> b;
			cin >> h;
			cout << "Pole trapezu wynosi " << (a + b) * h / 2;

		} break;
	default:
		{
			cout << "Wrong operation number selected\n";
		}
	}



	return 0;
}