Problem:
Circle

Write a program which calculates the area and circumference of a circle for given radius r.

Input

A real number r is given.

Output

Print the area and circumference of the circle in a line. Put a single space between them. The output should not contain an absolute error greater than 10-5.

Constraints

0 < r < 10000

Sample Input 1

2

Sample Output 1

12.566371 12.566371

Sample Input 2

3

Sample Output 2

28.274334 18.849556

Solution in C# (judge verdict: Accepted)

using System;

namespace ITP1_4_B
{
    class Program
    {
        static void Main(string[] args)
        {
            const double pi = 3.141592653589;
            string str = Console.ReadLine();
            double r = double.Parse(str);
            Console.WriteLine("{0:f8} {1:f8}", pi * r * r, pi * r * 2);
        }
    }
}