function slideshow_ajax() {
  global $values, $options;
    $count = count($values);
      if($count == 1) {
        array_push($values, '1');
      }
}

function slideshow_jquery() { ?>
<script type="text/javascript">
jQuery(document).ready(function($) {

	  jQuery('#slideshow_button').click(function() {
		  jQuery.post(ajaxurl, { action:"slideshow_action" });
		  return false;
	  });

	});
</script><?php
}
function slideshow_meta_box() {
  global $post, $options, $values;
  
  $meta_box_value = get_post_meta($post->ID, 'slideshow', true);
  
  $options = explode(",", $meta_box_value);
  
  ?><input type="hidden" name="slideshow_noncename" id="slideshow_noncename" value="<?php echo wp_create_nonce('slideshow_nonce'); ?>" /><?php
  
  $values = array('0');
 
  foreach($values as $value) { ?>
  <div style="position: relative; margin: 10px 10px 0 0;">
  <input type="text" id="Image" style="position: relative; right: 0; width: 85%;" name="slideshow[<?php echo $value; ?>]" value="<?php echo $options[$value]; ?>" />
  </div>
  <?php } ?>
  
  <input type="button" id="slideshow_button" name="slideshow_button" value="Add Image" /><?php 
}

add_action('wp_ajax_slideshow_action', 'slideshow_ajax');
add_action('admin_head', 'slideshow_jquery');