using System;

public class Program

{

    public static void Main()

    {

        Rectangle r = new Rectangle();

        r.Length = 10.0;

        r.Width = 20.0;

        double area = r.GetArea();

        Console.WriteLine("The area of the rectangle is {0} ", area + ".");

        r.FunFact();

    }

    class Rectangle{

        private double length;

        private double width;

        public double Length{

            get{

                return length;

            }

            set{

                if(value > 0.0){

                    length = value; 

                }

            }

        }

        public double Width{

            get{

                return width;

            }

            set{

                if(value > 0.0){

                    width = value;  

                }

            }

        }

        public double GetArea(){

            return length*width;    

        }

        public void FunFact(){

            Console.WriteLine("Did you know all squares are rectangles, but not all rectangles are squares?");

        }

    }

}