title: Meaning of stack[-1][0] in Python
body: <p>I'm new to python and I'm trying to understand a piece of code but I don't understand what the s[-1][0] means.</p>
  <pre><code>s = [ ];
  while(len(s)&gt;0 and s[-1][0] &lt;= el):
  </code></pre>
  <p>el is an int variable from and array.</p>