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: Accepted)

import java.util.*;
public class Main {
	public static void main(String[] args){
      	//データ取り込み
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
    	//int M = sc.nextInt();
      	//String S = sc.next();
      	//int list[] = new int[N];
      	//for(int i=0;i<N;i++){
        //	list[i] = sc.nextInt();
        //}
      	//Arrays.sort(list);
		if(N%2==0){
        	System.out.println(N);
        }else{
        	System.out.println(N*2);
        }
      	
    }
}