using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
double l;
Console.Write("vvedite d");
int d = Convert.ToInt32(Console.ReadLine());
l = Math.Pow((pi*d),2);
Console.WriteLine("l = " + l);
Console.ReadKey(); }
}