Repeater count or unique id

I'm probably overlooking some template tag, but is there any way to output a count or indexing in a repeater? I want every repeater item to have a unique id, this can be a count or a unique repeater item id, that doesn't really matter.

The goal is to have something like this in a repeater;

<div class="list">
   <div class="item-UNIQUE-NUM"></div>
   <div class="item-UNIQUE-NUM"></div>
   <div class="item-UNIQUE-NUM"></div>
</div>