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

An alphabetical continuous string is a string consisting of consecutive letters in the alphabet. In other words, it is any substring of the string "abcdefghijklmnopqrstuvwxyz".

For example, "abc" is an alphabetical continuous string, while "acb" and "za" are not.

Given a string s consisting of lowercase letters only, return the length of the longest alphabetical continuous substring.
 
Please complete the following python code precisely:
```python
class Solution:
    def longestContinuousSubstring(self, s: str) -> int:
```