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# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
					
public class Program
{
	public static void Main()
	{
		string n = Console.ReadLine();
		
		int result = 0;
		if((Convert.ToInt32(n) % 2) == 0){
			result = Convert.ToInt32(n);
		
		}else{
			result = Convert.ToInt32(n) * 2;
		}
		
		Console.WriteLine(result);
	}
}