p03307 AtCoder Beginner Contest 102 - Multiple of 2 and N
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.

Examples

Input

3


Output

6


Input

10


Output

10


Input

999999999


Output

1999999998
```python
n = int(input())
if n % 2 == 0:
  print(n)
else:
  print(2*n)
```