title: Verify 'X' number of digits have been inputted in batch script
body: <p>Writing a batch script.  How can I verify '3' NUMERIC digits have been inputted by a user with the "/p" prompt?</p>
  
  <p>Prompt to user:</p>
  
  <pre><code>SET /P SITEID=ENTER SITE # (i.e. 001 - MUST BE 3 DIGITS): 
  </code></pre>
  
  <p>I need to verify 3 digits have been inputted, if good continue with script. If NOT good re-prompt user to message of my choosing.</p>