public static void Main()
        {
            XYCoord t1 = new XYCoord();
            XYCoord t2 = new XYCoord(8, 9);
            XYCoord t3 = new XYCoord(t2);

            Console.WriteLine("t1.x, t1.y: " + t1.x + ", " + t1.y);
            Console.WriteLine("t2.x, t2.y: " + t2.x + ", " + t2.y);
            Console.WriteLine("t3.x, t3.y: " + t3.x + ", " + t3.y);
        }
 public XYCoord(XYCoord obj) : this(obj.x, obj.y)
 {
     Console.WriteLine("Внутри конструктора XYCoord(obj)");
 }