Problem:
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

Solution in C (GCC 5.4.1) (judge verdict: Accepted)

#include<stdio.h>
int main() {
	int i=0, n, ans;
	scanf("%d", &n);
	/*while (1) {
		i++;
		if((i % 2 == 0) && (i%n == 0)) {
				ans = i;
				break;
		}
	}*/
	if (n % 2 == 0) {
		ans = n;
	}
	else {
		ans = 2 * n;
	}
	printf("%d\n", ans);

}