title: get the second element that I search in a list
body: <p>I use python and I have a list of numbers and I would like to search a number X but I must find the second one element and if it doesn't exist I must get a msg </p>
  
  <p>Example: </p>
  
  <pre><code>list: [5, 6, 8, 7, 9, 6, 7, 9, 2, 4, 6, 8]
  
  X = 6
  
  return: i = 5
  
  </code></pre>
  
  <p>Ps: I need the faster code because I need to repeat it in a loop of 200000 i</p>