[jQuery] How to find the index of the parent of a specific element

[jQuery] How to find the index of the parent of a specific element


My question is quite simple with an example:
<div id="mymenu">
<ul>
<li><a id="link_x" href="#">label X</a></li>
<li><a id="link_y" href="#">label Y</a></li>
<li><a id="link_z" href="#">label Z</a></li>
<li><a id="link_w" href="#">label W</a></li>
</ul>
</div>
I would like to know the index of the <li> tag containing the
hyperlink with id "link_y" : in this example, it should be 1, but if
for any reason I re-order the links, alphabetically for example, it
should become 2.
Thanks for your help!
-- J:o)