title: Split 5 or 6 character number before fourth-last number
body: <p>I get POST request date strings in the format of <code>mY</code> (no leading zeros on the month), so there's no delimiting character to split on.</p>
  <p>Examples: <code>122019</code> or <code>62019</code></p>
  <p>I need to separate the five or six digit string into a one or two digit month and a four digit year.</p>
  <p>Eg1 :  122019</p>
  <pre><code>$a[0] = 12;
  $a[1] = 2019
  </code></pre>
  <p>Eg2 : 62021</p>
  <pre><code>$a[0] = 6;
  $a[1] = 2021
  </code></pre>