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 Python (3.4.3) (judge verdict: Runtime Error)

import numpy as np
from statistics import median
N = int(input())
A = list(map(lambda x:int(x),input().split(" ")))
npA = np.array(A)
B = npA-(1+np.arange(len(npA)))
opt_b = median(B)
print(int(np.sum(np.abs(B-opt_b))))