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.io.PrintWriter;
        import java.util.ArrayList;
        import java.util.Collections;
        import java.util.List;
        import java.util.Scanner;

public class Main {
    static private Scanner scan = new Scanner(System.in);
    public static void main(String args[]) {
        int int1 = Integer.parseInt(scan.next());
        int ans = 0;
        if(int1%2==0){
            ans = int1;
        }else{
            ans = int1*2;
        }
        PrintWriter out = new PrintWriter(System.out);
        out.println(ans);
        out.flush();
        scan.close();
    }
}