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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