using System;

​

public delegate double Calcul (double r);

public class Program

{

    static double Arie (double r)

    {

        return System.Math.PI*r*r;  

    }

    static double Lungime (double r)

    {

        return System.Math.PI*2*r;  

    }

    public static void Main()

    {

        Calcul a = new Calcul(Arie);

        Console.WriteLine("{0:#.##}",a(2));

        Calcul b = new Calcul(Lungime);

        Console.WriteLine("{0:#.##}",b(4));

    }

}