title: Negate part of regex
body: <p>I'm looking for a way to match (pseudo code)</p>
  
  <pre><code>grep -E '^[aoueiy]*(!sch|s|z)+.*$'
  </code></pre>
  
  <p>where <code>!</code> is no match</p>
  
  <p>It should match <code>sabc</code>, <code>zabc</code> and <code>as</code>, but not <code>usch</code>.</p>
  
  <p>How can I write this in a proper way with grep?</p>