Conditional for putting ads after 1st and third posts

[bacemail]

Right now, I have ads appearing after the first post in a thread which looks like this...

<if condition="$post[postcount] == 1 AND !$bbuserinfo[userid]">

I want to make a conditional that also places an ad after the 3rd post.

Can I change the conditional by adding an OR?

<if condition="$post[postcount] == 1 || 3 AND !$bbuserinfo[userid]">

Thanks in advance.

--------------- Added [DATE]1323637862[/DATE] at [TIME]1323637862[/TIME] ---------------

I think I have it, but I'm to chicken to test it out live.

How does this look?

<if condition="$post[postcount] % $vboptions[maxposts] == 1 || $post[postcount] % $vboptions[maxposts] == 3 AND !$bbuserinfo[userid]">