title: Query for an exact number of relationships
body: <p>I'm trying to figure out the proper Cypher queries for group chat which I have modeled as follows:</p>
  
  <pre><code>(u:user)-[:in_conversation]-&gt;(c:conversation)
  (c:conversation)-[:has_message]-&gt;(m:message)
  </code></pre>
  
  <p>So if 3 users are in a conversation, I'd have 3 users who have the <code>in_conversation</code> relationship.</p>
  
  <p>What is the best way to find or create a conversation for a given list of people</p>
  
  <p>For example, I might have a conversation between userA and userB but <strong>also</strong> have a conversation between userA, userB, and userC.</p>
  
  <p>So if I'm looking to grab the userA-userB conversation, I wouldn't want to grab the userA-userB-userC conversation by accident just because it has the proper relationships.</p>