title: Bitwise comparison for 16 bitstrings
body: <p>I have 16 unrelated binary strings (of the same length). eg. 100000001010, 010100010010 and so on, and I need to find out a bitstring in which position x is a 1 IF position x is 1 for ATLEAST 2 bitstrings out of the 16.</p>
  
  <p>Initially, I tries using bitwise XOR and this works great as long as even number of strings contain a 1, but when odd number of strings contain 1, the answer given is reverse.</p>
  
  <pre><code>A simple example (with 3 strings) would be:
  A: 10101010
  B: 01010111
  C: 11011011
  
  f(A,B,C)= answer
  
  Expected answer: 11011011
  Answer I'm getting right now: 11011001
  </code></pre>
  
  <p>I know I'm wrong somewhere but I'm at a loss on how to proceed
  Help much appreciated</p>