Problem:
Score : 100 points

Problem Statement

Print the circumference of a circle of radius R.

Constraints

1 \leq R \leq 100

All values in input are integers.

Input

Input is given from Standard Input in the following format:

R

Output

Print the circumference of the circle.
Your output is considered correct if and only if its absolute or relative error from our answer is at most 10^{-2}.

Sample Input 1

1

Sample Output 1

6.28318530717958623200

Since we accept an absolute or relative error of at most 10^{-2}, 6.28 is also an acceptable output, but 6 is not.

Sample Input 2

73

Sample Output 2

458.67252742410977361942

Solution in Scala (2.13.1) (judge verdict: Accepted)

import scala.math

object Main {
	def main(args: Array[String]) {
		val input = io.Source.stdin.getLines().mkString("\n")
		println(solve(input).trim)
	}

	def solve(input: String): String = {
		 val a = input.toInt
		 val ans = a * 2 * math.Pi
		 ans.toString
	}

}