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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		//String s = sc.next();
		//String t = sc.next();
		//String g = sc.next();
		long n = sc.nextLong();
		//long m = sc.nextLong();
		//long k = sc.nextLong();
		//long l = sc.nextLong();
		long count=0;

		/*for(int i=0;i<=3;i++) {
			if(s.substring(i,i+1).equals("+")) {
				count++;
			}else {
				count--;
			}
		}*/
		if(n%2==0) {
			System.out.println(n);
		}else{
			System.out.println(n*2);
		}
		//System.out.println((int)Math.ceil((n+m)/2.0));
		System.out.println(count);
	}
}