counting tags inside a <iframe>

counting tags inside a <iframe>

Hi,
I am a newbie to jquery i want to count some tags inside a <iframe>.
The iframe src is like this
<iframe src="http://mysite.com/testing.php?id=7632762"></iframe>
the php file included in the source contains several include files and more php kinda script finally a html output is generated.How to count the tags this generated html ??

-Thank you.