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 JavaScript (Node.js 12.16.1) (judge verdict: Accepted)

"use strict";
function main(input) {
    var line = input.split("\n");
    const pi = 3.14159265359;
    let R = parseInt(line[0]);
    var circumference = 2*pi*R;
    console.log(circumference.toPrecision(20));
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));