I'm new to being a free tutor, get a tutorial on arrays and hashes. :-) Seriously, it is some advanced code work ( which by the way, I did not write....it's been passed around in books and tutorials for a long time. The general idea is to check all array elements...dump them in a hash for counting, then check the hash keys (an array) for 1's or 0's....(or something along those general lines).

Probably every programming language has some sort of "array comparison" abilities... google for "perl array comparison", grasshopper, and when you are done reading all 5 million hits....come back and teach me. :-)