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 AOZ
{
	class MainClass
	{
		static void Main(string[] args)
		{
			var input_arr = Console.ReadLine().Split(' ');
			double r = double.Parse(input_arr[0]);
			double area = Math.PI * Math.Pow(r, 2);
			double circumference = 2 * Math.PI * r;
			Console.WriteLine($"{area:F6} {circumference:F6}");
		}
	}
}