title: Python 3 with large integers
body: <p>I use Python to handle some large integers (64-bit, unsigned). I'm trying to convert a string of values to integers. However my Python3 gave me incorrect results. 
  For example, if I convert an input string of "12736193479609682490" to integer, the result is not what I expected:</p>
  
  <pre><code>a = '12736193479609682490'
  b = int(float(a))
  
  &gt;&gt;&gt;b
  12736193479609681920
  </code></pre>
  
  <p>I'm usng Python 3.4.0 under ubuntu 12.04-64bit. What should I do to make a correct conversion? Thanks.</p>