PHP: Adding (even|odd), first & last classes to markup in a foreach loop.

foreach.php

 <ul>      
   <?php $c_schools = count( $district['School'] ) ?>
   <?php foreach( $district['Plan'] as $i => $plan ): ?>
     <?php $classes = array( $i % 2 == 0 ? 'odd' : 'even' ) # Adjusted for 0-based indexing ?>
     <?php array_push( $classes, $i == 0 ? 'first' : false ) ?>
     <?php array_push( $classes, $i == $c_schools - 1 ? 'last' : false )?>
        
     <li class="<?php echo join( ' ', array_filter( $classes ) ) ?>">
       PLAN NAME HERE        
     </li>
   <?php endforeach; ?>
 </ul>