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: Accepted)


function Main(input) {

	input = input.split("\n");

	var n = parseInt(input[0], 10);

	if (n & 1)
	{
		console.log('%d',n*2);
	}
	else
	{
		console.log('%d',n);
	}

}

Main(require("fs").readFileSync("/dev/stdin", "utf8"));