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 Ai[N];
    int i, tempmax, tempmin;
        for (i = 0; i < N; i++){
            scanf("%d",&Ai[i]);
        }
        tempmax = Ai[0];
        tempmin = Ai[0];
        for (i = 0; i < N; i++){
            if (Ai[i] > tempmax)
            tempmax = Ai[i];
            if (Ai[i] < tempmin)
            tempmin = Ai[i];
        }
        printf("%d\n",tempmax - tempmin);
    return 0;
}