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()
        {
            var r = double.Parse(Console.ReadLine());
            
            //円の面積=半径×半径×円周率
            //円周の長さ=直径×円周率
            double f = 3.141592653589;
            
            double s = r * r * f;
            double p = 2 * r * f;
            
            Console.WriteLine("{0} {1}", s, p);
        }
    }
}