using System;

​

namespace CircleProgram

{

    abstract class AbsClass

    {

        public const double pi = 3.14;

        public abstract double FindArea(double Side1);

    }

    class AreaOfCircle : AbsClass

    {

        public override double FindArea(double Side1)

        {

            return   pi*(Side1*Side1);

        }

    }

    class Circumference : AbsClass

    {

        public override double FindArea(double Side1)

        {

            return 2 * Side1 * pi;

        }

    }

​

    class Circle

    {

        static public void Main()

        {

            double side1;

            Console.WriteLine("Enter Radius of Circle: ");

            side1 = Convert.ToDouble(Console.ReadLine());

            AreaOfCircle a = new AreaOfCircle();

            Console.WriteLine("Area of a Circle: {0} ", a.FindArea(side1));

            Console.ReadLine();

            Circumference b = new Circumference();

            Console.WriteLine("Circumference of a Circle: {0}" , b.FindArea(side1));

            Console.ReadLine();

        }

    }

}