title: ValueError: invalid literal for long() with base 10: ''
body: <p>How do I get this to work?</p>
  
  <pre><code>n = 1234
  f = open("file", "r")
  while True:
   x=f.readline()
   print "*********************"
   print n%(long(x))
   if n%(long(x))==0:
     print x
  else:
   print "..."
  </code></pre>
  
  <p>I'm a noob in python and I'm getting an error I don't understand. What am I doing wrong?</p>
  
  <pre><code>ValueError: invalid literal for long() with base 10: ''
  </code></pre>