An integer divisible by the sum of its digits is said to be a Harshad number. You are given an integer x. Return the sum of the digits of x if x is a Harshad number, otherwise, return -1.
Example 1:
Input: x = 18
Output: 9
Explanation:
The sum of digits of x is 9. 18 is divisible by 9. So 18 is a Harshad number and the answer is 9.
Example 2:
Input: x = 23
Output: -1
Explanation:
The sum of digits of x is 5. 23 is not divisible by 5. So 23 is not a Harshad number and the answer is -1.
Constraints:
1 <= x <= 10018 23