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";

var processData = function processData(lines) {
  var r = +lines[0];
  console.log(r * Math.PI * 2);
};

var i = '';
process.stdin.on('data', function (c) {
  return i += c;
});
process.stdin.on('end', function () {
  var _require = require('os'),
      EOL = _require.EOL;

  var lines = i.split(EOL);
  /*your input text, split by lines*/

  processData(lines);
});