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-----
3

-----Sample Output-----
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.

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