title: subtract a pattern in Elixir
body: <p>I am trying to subtract a pattern in Elixir.</p>
  
  <p>I have 2 file names as <code>30_01_000.jpg</code> and <code>30_00_000.jpg</code> in which 30 are minutes , 01 &amp; 00 are seconds. What I am trying to achieve is to find the difference between them, as it's obvious, the difference is 1 second. But I could have one file as <code>40_01_000.jpg</code> and the other one could be <code>50_01_000.jpg</code>. So I want a dynamic way to do this.</p>
  
  <p>The strategy behind this is: I requested a file for <code>30_00_000.jpg</code> (through actual timestamp in Unix) BUT the available one is <code>30_01_000.jpg</code> So If I will find the difference I can add it to Unix timestamp of the first file so It will get the next one available. </p>
  
  <p>So is that possible to do so? in anyway? Any help will be thankful</p>