title: Execute Crontab every 1 and 15 of every month
body: <p>I used to run a script every week, but now I need to run it twice in every month.</p>
  
  <p>My current commands are:</p>
  
  <p><strong>30 5 * * 1 "command"</strong></p>
  
  <p>Now I want to run my "command" every 1st and 15th of every month. I do not know what values to put in the third option, the days option.</p>