//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public interface Geo
    {
       double arie(double x);
       double perimetru(double x);
    }
    public class cerc : Geo
    {double r;
     double arie(double r)
     {return r*r*System.Math.PI;


     }
     double perimetru(double r)
     {
         return 2*r*System.Math.PI;
     }
     public cerc(double x)
     {

         r=x;
     }



    }

    public class Patrat : Geo
    {double l;
     double arie(double l)
     {


     }
    public class Program
    {
        public static void Main(string[] args)
        {

        }

    }
}