<?php if( get_row_layout() == 'flex_field' ):
$row_count = count(get_sub_field('repeater');
if( have_rows('repeater') ): ?>
<div class="repeater-wrapper <?php echo 'rows-.$row_count'; ?>">
<?php while ( have_rows('repeater') ) : the_row(); ?>
<div class="repeater-row">
<p><?php the_sub_field('repeater_row_content'); ?></p>
</div>
<?php endwhile; ?>
</div>
<?php endif;
endif; ?>