How to display Ads Between Posts in Blogger Layout v3?

Question

I just try to customize the latest Blogger v3 and it's a bit different. In v2 I just need to put the ads between loop like this:

<b:includable id='main' var='top'>
  ....
  ....
  <b:loop values='data:posts' var='post' index='infeed'>
    <div class='date-outer'>
      <b:if cond='data:view.isMultipleItems'>
        <b:if cond='data:infeed == 3'>
          <div class='post'>
          <!-- ADS HERE -->
          </div>
          &lt;/div&gt; &lt;div class=&quot;date-outer&quot;&gt;
        </b:if>
      </b:if>
    </div>
  </b:loop>
  ....
  ....
</b:includable>

It will put ads AFTER the 3rd post.

How to do it in Blogger layout v3 since I didn't see any <b:loop> condition like that?