first and last wordpress menu item

gistfile1.php

function add_menu_parent_class( $items ) {

	// GET PARENT ITEMS
    $parents = array();
		foreach ( $items as $item ) {
			if ( $item->menu_item_parent && $item->menu_item_parent > 0 ) {
				$parents[] = $item->menu_item_parent;
			}
		}

	// COUNT PARENT ITEMS
	$count = 0;
		foreach ( $items as $item ) {	
			if (in_array( $item->ID, $parents )) {
				$count++;
			}
		}

	// ADD CLASSES TO FIRST AND LAST PARENT LI TAGS
	$i = 1;
		foreach ( $items as $item ) {
			if ( in_array( $item->ID, $parents ) ) {
					if ($i == 0) {
						$item->classes[] = 'first-menu-parent-item';
					}
					if ($i == $count) {
						$item->classes[] = 'last-menu-parent-item';
					}
				$i++;
			}
		}
    return $items;
}
add_filter( 'wp_nav_menu_objects', 'add_menu_parent_class' );