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