Given a positive integer
n, return the smallest positive integer that is a multiple of both 2 and n.
Example 1:
Input: n = 5 Output: 10 Explanation: The smallest multiple of both 5 and 2 is 10.
Example 2:
Input: n = 6 Output: 6 Explanation: The smallest multiple of both 6 and 2 is 6. Note that a number is a multiple of itself.
Constraints:
1 <= n <= 150