Remove spam url in text
<p>Input:</p>

<blockquote>
  <p>dsfdsf www. cnn .com dksfj kdsfjkdjfdf
  www.google.com dkfjkdjfk w w w . ya
  hoo .co mdfdd</p>
</blockquote>

<p>Output:</p>

<blockquote>
  <p>dsfdsf  dksfj kdsfjkdjfdf  dkfjkdjfk  mdfdd</p>
</blockquote>

<p>How do I write a function that does this in C#?</p>
