title: find the smallest period in list of dates
body: <p>is there a way an idea to find the smallest period in list of dates:</p>
  <pre><code>A: startDate|----------------------|EndDate
  B: startDate|------------|EndDate
  C: startDate|-----------------|EndDate
  </code></pre>
  <p>the smallest period is in this exemple is B.
  I need an idea to begin</p>