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: Runtime Error)

import java.util.*;

public class Main {
 public static void main(String[] args) {
  Scanner sc = new Scanner(System.in);
  int num = sc.nextInt();
  int[] numbers = new int[num];
  for (int i = 0; i < num; i++) {
   numbers[i] = sc.nextInt();
  }
  int b = -100;
  int lastSorrow = calcSorrow(numbers, b);
  while (calcSorrow(numbers, b) > lastSorrow) {
      lastSorrow = calcSorrow(numbers, b);
      System.out.println(lastSorrow);
      b++;
  }
  System.out.println(lastSorrow);
 }
 
 private static int calcSorrow(int[] numbers, int b) {
   int kanashimi = 0;
   for (int i=0; i<numbers.length; i++) {
       kanashimi += Math.abs(numbers[i] - b - i - 1);
   }
   return kanashimi;
 }
}