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 (GCC 5.4.1) (judge verdict: Accepted)


#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>


int main(void)
{
	//変数の宣言
	
	//int n,k;
	
	int N;
	
	//データの読み込み
	//scanf("%d %d",&n,&k)
	
	scanf("%d",&N);
	
//	printf("nは%dです\n", n);
//	printf("データの読み込み終了\n");
	//実際の処理
	
	if(N%2==0){
		printf("%d",N);
	}else{
		printf("%d",N*2);
	}
	
//	printf("計算部分終了\n");
	
	//出力
	
	
	
//	printf("結果の出力終了\n");
	
	return 0;
}