public void GetArea()
{
Rectangle shape;
shape = new Square();
shape.SetWidth(5);
shape.SetHeight(10);
Console.WriteLine("Area={0}", shape.getArea()); // ??
Console.ReadLine();
}
static void Main(string[] args)
{
Rectangle rectangle = new Rectangle(10, 5);
Console.WriteLine(rectangle.ComputeArea());
Square square = new Square(10);
Console.WriteLine(square.ComputeArea());
Rectangle rectangle2 = new Square(10);
rectangle2.SetHeight(3);
Console.WriteLine(rectangle2.ComputeArea());
Console.Read();
}