template navigation problem

hello,
iam doing a wordpress template and would like to have a navigation on the top of my side like

< li class=”button seperator”>Page1< /li >
< li class=”button seperator”>Page2< /li >
< li class=”button seperator”>Page3< /li >
< li class=”button”>Page4< /li >

the last li-tag should always not have the class seperator, because its a border to the right how do i realize that?

thank you.
regards