jQuery: how to get the number/position of an element : In my HMTL page I have this list

    <ul>
      <li id=a></li>
      <li id=b></li>
      <li id=c></li>
      ...
    </ul>

How can I do in jQuery to get the "position" (meant as n-th son) of a tag knowing its id? For example something like:

    $(#c).position() = 3
    
meant that $(#c) is the 3-rd son of <ul>. Is it possible?