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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include<iostream>
#include<algorithm>
#include<cmath>
#include<string>
int main()
{
	long long a = 0, b = 0, c = 0, tower[1000] = {0}, last = 0, k = 0, ansa = 0, ansb = 0, x = 0, y = 0, mi[1000] = {};
	
	int snow=0;
		int one = 0, ten = 0, hun = 0, thou = 0,man=0;
	std::cin >>a;
	
	bool okada = true;
	if (a % 2 == 0) {
		std::cout << a << std::endl;
	}
	else {
		std::cout << a * 2 << std::endl;
	}
	

}