private void TotalAreaCalculating(int a, int b, int h)
        {
            Rectangle rectangle = new Rectangle(a, b);
            Cuboid cuboid = new Cuboid(a, b, h);
            TriangularPrism prism = new TriangularPrism(a, h);
            double RectanglesArea = rectangle.Area();
            double CuboidsArea = cuboid.Area();
            double PrismsArea = prism.Area();
            Console.WriteLine("\r\nTotal area of all figures: "
                + Math.Round((RectanglesArea + CuboidsArea + PrismsArea), 3));
        }