Problem:
Score : 100 points

Problem Statement

You are given a positive integer N.
Find the minimum positive integer divisible by both 2 and N.

Constraints

1 \leq N \leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N

Output

Print the minimum positive integer divisible by both 2 and N.

Sample Input 1

3

Sample Output 1

6

6 is divisible by both 2 and 3.
Also, there is no positive integer less than 6 that is divisible by both 2 and 3.
Thus, the answer is 6.

Sample Input 2

10

Sample Output 2

10

Sample Input 3

999999999

Sample Output 3

1999999998

Solution in JavaScript (node.js v5.12) (judge verdict: Runtime Error)

function main(input) {
  var input = input.split('\n')[1];
  var max = 0;
  var min = 10000000000;
  for (var i=0;i<input.length;i++){
  	var tmp = parseInt(input[i]);
  	if (tmp > max) {
  		max = tmp;
  	}
  	if (tmp < min) {
  		min = tmp;
  	}
   	
  }
  console.log('0');