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 ITP1
{
    class ITP1_4_B
    {
        static void Main(string[] args)
        {
            double area, circle;

            double r = double.Parse(Console.ReadLine());

            area = (Math.Pow(r, 2)) * Math.PI;
            circle = (r * 2) * Math.PI;

            Console.WriteLine($"{area} {circle}");
        }
    }
}