element
      <tt>x</tt>.</td>
    </tr>

    <tr>
      <td><tt>template &lt;class ElementIterator&gt;<br>
      std::size_t count_sets(ElementIterator first, ElementIterator
      last)</tt></td>

      <td>Returns the number of disjoint sets.</td>
    </tr>

    <tr>
      <td><tt>template &lt;class ElementIterator&gt;<br>
      void compress_sets(ElementIterator first, ElementIterator
      last)</tt></td>

      <td>Flatten the parents tree so that the parent of every element is its
      representativ