title: How to check dash after repeating groups in regex
body: <p>Sample string:</p>
  <pre><code>MON,00:00-10:00-11:00-13:00-15:00-16:00;TUE,00:00-23:59;
  </code></pre>
  <p>Regex:</p>
  <pre><code>^((MON|TUE|WED|THU|FRI|SAT|SUN),(([01][0-9]|2[0-3]):([0-5][0-9])-([01][0-9]|2[0-3]):([0-5][0-9]))+;)+$
  </code></pre>
  <p>Here I want to check dash is there (not optional) after every interval of start and end time.</p>
  <blockquote>
  <p>00:00-10:00<br />
  11:00-13:00<br />
  15:00-16:00</p>
  </blockquote>
  <p>So the above will be</p>
  <pre><code>00:00-10:00-11:00-13:00-15:00-16:00
  </code></pre>