title: Python Subtracting Elements in a Lists from Previous Element
body: <p>I have a loop that produces multiple lists such as these:</p>
  
  <pre><code>  [1,6,2,8,3,4]
  
    [8,1,2,3,7,2]
  
    [9,2,5,6,1,4]
  </code></pre>
  
  <p><em>For each list, I want to subtract the first two elements, and then use that value to then subtract the third element from.</em> </p>
  
  <p>For example, the first list should end up looking like:</p>
  
  <pre><code>  [-5, 4,-6, 5,-1]
  </code></pre>
  
  <p>I have tried to manually do this, but there are too many lists to do this and it would take too much time. </p>
  
  <p>How would I do that in the least amount of lines of code?</p>