adding ads code between comments

I am showing comments on my page. I want to show 1 ad after every 2 comments.

<div class="panel-footer clearfix"></div> it’s repeating the number of comments.

I would like to add the ad code after every 2 comments.

For example:

<div class="panel-footer clearfix"></div> <div class="panel-footer clearfix"></div>  /*  * My ads code  */  <div class="panel-footer clearfix"></div> <div class="panel-footer clearfix"></div>  /*  * My ads code  */ 

My wp_list_comment() function:

<?php function sinyor_comment($  comment, $  args, $  depth,$  i=0) {      $  GLOBALS['comment'] = $  comment;     $  PostAuthor = false;       if($  comment->comment_author_email == get_the_author_email()){         $  PostAuthor = true;     }elseif($  comment->comment_author_email == 'mailadresiniz@mail.com'){         $  PostAuthor = true;     }  ?>  <div class="panel panel-default entry" id="comment-<?php echo $  comment->comment_ID; ?>"  itemprop="suggestedAnswer" itemscope itemtype="http://schema.org/Answer">     <div class="panel-body">         <div itemprop="text"> <?php comment_text(); ?> </div>     </div>     <div class="panel-footer clearfix">         /*          *   My wp comment codes are here          */     </div> </div>  <?php  }