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 $N$.

The first line of input contains the integer $N$ ($1 \leq N \leq 10^9$).

Print the minimum positive integer divisible by both $2$ and $N$.

Input

3

Output

6

Input

10

Output

10

Input

999999999

Output

1999999998