<p>An <strong>alphabetical continuous string</strong> is a string consisting of consecutive letters in the alphabet. In other words, it is any substring of the string <code>"abcdefghijklmnopqrstuvwxyz"</code>.</p>
<ul>
<li>For example, <code>"abc"</code> is an alphabetical continuous string, while <code>"acb"</code> and <code>"za"</code> are not.</li>
</ul>
<p>Given a string <code>s</code> consisting of lowercase letters only, return the <em>length of the <strong>longest</strong> alphabetical continuous substring.</em></p>