using System; //namespace declaration

​

public class Program

{

    public static void Main()

    {

        Circle c1 = new Circle(5);

        float result1 = c1.CalculateArea();

        Console.WriteLine("Area={0}", result1);

        Circle c2 = new Circle(6);

        float result2 = c2.CalculateArea();

        Console.WriteLine("Area={0}", result2);

        Console.WriteLine("circumference={0}", c1.Circum());

    }

}

​

public class Circle

{

    //members of this class

    static float pi;

    static int radius;

    int rc;

    static Circle()

    {

        //static constructors will allow only static mems within it

        radius = 5;

         pi=3.141F;

    }

​

    public Circle(int circum)

    {

        rc = circum;

    }

​

    public float Circum()

    {

        return 2 * pi * rc;

    }

​

    public float CalculateArea()

    {

        return pi * radius * radius;

    }

}