Please solve the programming task below using a self-contained code snippet in a markdown code block.

We are given hours, a list of the number of hours worked per day for a given employee.
A day is considered to be a tiring day if and only if the number of hours worked is (strictly) greater than 8.
A well-performing interval is an interval of days for which the number of tiring days is strictly larger than the number of non-tiring days.
Return the length of the longest well-performing interval.
 
Please complete the following python code precisely:
```python
class Solution:
    def longestWPI(self, hours: List[int]) -> int:
```