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: Runtime Error)

#include<stdio.h>
 
int main(void)
{
    int n; scanf("%d",&n);
  	int a[n];
  	int max,min;
  	int i;
	scanf("%d",&a[0]);
  	min=a[0];
    max=a[0];
    for(i=1;i<n;i++){
        scanf("%d",&a[i]);
        if(max<a[i]){
            max=a[i];
        }
        if(min>a[i]){
            min=a[i];
        }
    }
    printf("%d\n",max-min);
    return 0;
}