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