using System;

public class Rectangle

{

    protected double length;

    protected double width;

    public Rectangle(double l, double w)

    {

        length = l;

        width = w;

    }

    public double GetArea()

    {

        return length * width;

    }

    public void Display()

    {

        Console.WriteLine("Length: {0}", length);

        Console.WriteLine("Width: {0}", width);

        Console.WriteLine("Area: {0}", GetArea());

    }

    class Tabletop : Rectangle

    {

        private double cost;

        public Tabletop(double l , double w) : base(l, w)

        {}

        public double GetCost()

        {

            double cost;

            cost = GetArea() * 70;

            return cost;

        }

        public void Display()

        {

            base.Display();

            Console.WriteLine("cost: {0}", GetCost());

        }

    }

    class ExecuteRectangle

    {

        static void main(String[] args)

        {

            Tabletop t = new Tabletop()(4.5, 7.5);

            t.Display();

            Console.ReadLine();

        }

    }

}