Length of the Longest Alphabetical Continuous Substring

Given a string, s, consisting of lowercase letters only, your task is to print the length of the longest alphabetical continuous substring.

An alphabetical continuous string is defined as a substring consisting of consecutive letters in the alphabet (i.e., "abcdefghijklmnopqrstuvwxyz"). For example, "abc" is an alphabetical continuous string, while "acb" and "za" are not.