title: Go back to the original number after the sum of values ​between two lists
body: <p>I wrote this code to sum a number and its reverse:</p>
  <pre><code>    #sum the multiple of the first number and its reversed
  
      zipped_lists = zip(primo, reversedList)
      res = [x + y for (x, y) in zipped_lists]
      print (res)
  
      #search common values in &quot;res&quot; and &quot;secondo&quot;
  
      common_list = set(res).intersection(secondo)
  
  </code></pre>
  <p>Now that I isolated significant numbers, I need to return to the original number listed in <code>primo</code>. I've no idea how to do that. Please, help me :(</p>