title: Regex that captures the text only if there is 3 lines
body: <p>I have this regex1 :</p>
  
  <pre><code>(\w+)\n#(\w+)_(\w+)\n(\w+)
  </code></pre>
  
  <p>That captures the following text1 : </p>
  
  <pre><code>randomtext
  #randomteeexxt_randomqlsdfjml
  randomagain
  </code></pre>
  
  <p>But sometimes I have a fourth line in the text2 :</p>
  
  <pre><code>randomtext
  #randomteeexxt_randomqlsdfjml
  randomagain
  stillrandom
  </code></pre>
  
  <p>So this following regex2 works :</p>
  
  <pre><code>(\w+)\n#(\w+)_(\w+)\n(\w+)\n(\w+)
  </code></pre>
  
  <p>The regex2 does not match anything of the text1, this is what I want.</p>
  
  <p>The regex1 matches the 3 first lines of the text2, but I don't want it.</p>
  
  <p>I want that the regex1 does not match anything of the text2.</p>