function total_number_comment() {

      global $post;
      $url = get_permalink($post->ID);

      $filecontent = file_get_contents('https://graph.facebook.com/?ids='.$url);
      $json = json_decode($filecontent);

      $fb_count = $json->$url->comments;
      if ($fb_count == 0 || !isset($fb_count)) {
          $fb_count = 0;
      }
      $wp_count = (int)get_comments_number();

      echo $fb_count + $wp_count;
  }

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    FB.init({
      appId      : 'ID',
      xfbml      : true,
      version    : 'v2.4'
    });
  };

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     var js, fjs = d.getElementsByTagName(s)[0];
     if (d.getElementById(id)) {return;}
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</script>