static void Main(string[] args)
{
// var quad1 = new Quadrillateral(2, 4, 6, 8);
var quad1 = new Quadrillateral {
Side1 = 2, Side2 = 4, Side3 = 6, Side4 = 8
};
quad1.Perimeter();
var rect1 = new Rectangle(5, 7);
rect1.Perimeter();
rect1.Area();
var sqr1 = new Square(6);
sqr1.Perimeter();
sqr1.Area();
}