Add the opening list tags in their correct position.

<html>
<body>
Marathon Results
<ol>
  <li>Winners
    <ul>
    <li>Weiss, Michael</li>
    <li>Tutukin, Ivan</li>
    <li>Potts, Andrew</li>
    </ul>
  </li>
</ol>
<ul>
  <li>Disqualified
    <ul>
    <li>Macheiner, Martin</li>
   </ul>
  </li>
</ul>
</body>
</html>]]>

Make sure to pick <ul>, followed by <li>, and finally <ul>.