title: substitute the even couple of <>
body: <pre><code>&lt;a&gt;&lt;b&gt;&lt;c&gt;&lt;d&gt;&lt;e&gt;
  </code></pre>
  
  <p>to</p>
  
  <pre><code>&lt;a&gt;b&lt;c&gt;d&lt;e&gt;
  </code></pre>
  
  <p>Any idea?</p>
  
  <p>I want to use perl substitute, but it's not correct.</p>
  
  <pre class="lang-sh prettyprint-override"><code>echo '&lt;a&gt;&lt;b&gt;&lt;c&gt;&lt;d&gt;&lt;e&gt;'|perl -pe's#&lt;|&gt;#$x+=3;$y+=4;(++$n==$x or ++$n==$y)?$&amp;:"*":'
  </code></pre>