Show the code that you have written so far.
As a general rule, the people helping out in this forum don't write code for others (especially code that appears to be for homework), but try to help with fixing code that doesn't work. You may perhaps get someone to write this script for you, but you'll be far more likely to get help if you have made a substantial effort and written some code yourself. Then someone here will almost certainly help you correct/improve your work.
All the code given in this post has been tested and is intended to address the question asked.
Unless stated otherwise it is not just a demonstration.
Last edited by Philip M; 01-17-2013 at 12:58 PM..