title: Find index of a given number in a list python3
body: <p>I've written a program that gives me the index of a given integer of my choosing (x) in a list. Also, when a given integer isn't in the list, I want the program to give me the output -1 (or None).</p>
  
  <pre><code>list = [7,13,6,1]
  x = 5
  for i,j in enumerate(list):
      if j==x:
              print(i)
      else:
              print(-1)
  </code></pre>
  
  <p>However. If I use this on for instance the list given above, the output will be</p>
  
  <pre><code>-1
  -1
  -1
  -1
  </code></pre>
  
  <p>Where I only want -1. Any thoughts?
  <strong>Update</strong>
  I also want the program to give me only the index of the first integer it finds, whereas it now gives me the index of all the numbers, equal to x, which it finds in the list</p>