title: Regular expression ignore strings start with a specific string
body: <p>I need to find all the words containing some string. For example "team" and replace it with another string.
  The string will as a substring for example:</p>
  
  <ol>
  <li>team of experts</li>
  <li>team manager</li>
  <li>A big team</li>
  </ol>
  
  <p>I need to replace all those places with the string <code>"hlhl$$@team"</code>.</p>
  
  <p>I use the regular expression:</p>
  
  <pre><code>String exp= String.Format("({0}\\s)|({0}$)", "team);
  </code></pre>
  
  <p>The problem is that strings that are already are <code>"hlhl$$@team"</code> match the regular expression and are being replaced to <code>"hlhl$$@hlhl$$@team"</code>
  How can I ignore those strings that start with <code>hlhl$$@</code>?
  Thanks.</p>