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

n = int(input())
a = list(map(int, input().split()))

a_d = []
for i in range(1, n+1):
    a_d.append(a[i-1]-i)

d = (list(np.absolute(a_d)))
d.sort()
m = d[int(n/2)]

print(abs(sum(d-m)))