<section id="mast" class="section bg-mast">
<?php if( have_rows('images') ): $count = 0; ?>
  <?php while( have_rows('images') ): the_row(); ?>
    <div class="slide <?php if (!$count) { ?>show<?php } ?>" style="background-image: url('<?php the_sub_field('image'); ?>');"><div class="caption"><a href="<?php the_sub_field('link'); ?>"><?php the_sub_field('caption'); ?></a></div></div>
  <?php $count++; endwhile; ?>
<?php endif; ?>
</section>