title: Comparing 2 queues and finding an element that does not exist in both queues
body: <p>I'm currently trying to compare 2 queues. Most of the entries in the queue will be duplicate (both queues will have the same entries). What I want to be able to do is, find an entry that does not exist in both queues.</p>
  
  <p>For example, assuming the following are the 2 queues in question.</p>
  
  <pre><code>1st queue - A S D F G
  2nd queue - S A D G Q
  </code></pre>
  
  <p>The entry A, S, D, G exists in both queue. However, the entry F is unique for the 1st queue, and Q is unique for the 2nd queue. I want to be able to find out which entries are unique. Is there a function that does something like this? </p>
  
  <p>For the sake of the question, I need to use a queue as the FIFO behavior is crucial.</p>