Fito is doing Math homework again. As usual, he would like to write a program that computes the answer automatically. He knows that the teacher might ask the students to solve thousands of them. Since Fito is new to programming, he needs your help!
Given a positive integer $N$, find the minimum positive integer divisible by both $2$ and $N$.
Input
The first line of input contains the integer $N$ ($1 \leq N \leq 10^9$).
Output
Print the minimum positive integer divisible by both $2$ and $N$.
Sample test(s)
Input
3
Output
6
Input
10
Output
10
Input
999999999
Output
1999999998