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;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace AOJHelloWorld1
{
    class Program
    {
        static void Main(string[] args)
        {
            double r = double.Parse(Console.ReadLine());//円の半径
            double π = Math.PI;//円周率
            double S = r * r * π;//円の面積
            double L = 2 * r * π;//円の周

            Console.WriteLine(S+" "+L);
        }
    }
}