title: Help!!! RegEx.Replace
body: <p>How do i achieve this directory format using the RegEx.</p>
  
  <pre><code>Input FileName(40 chars) : 000a2d0e62e43b0f680a6eb6019f9671b15ca291
  
  output should looks like this: 00\0a2\d0e\62e43  
  get only the first 13th character.
  </code></pre>
  
  <p>Thanks a lot.</p>
  
  <p>johnL</p>