Kata

Given a string of characters, create a function returning the middle number in the product of each digit in the string.

Example: 's7d8jd9' -> 7, 8, 9 -> 7*8*9=504, thus 0 should be returned as an integer.

Not all strings will contain digits and not all inputs will be string. In those cases, return -1.

If the product has an even number of digits, return the middle two digits

Example: 1563 -> 56

NOTE: Remove leading zeros if product is even and the first digit of the two is a zero. Example 2016 -> 1