Your post seems so very specific that if I was cynical I would suspect this was some sort of assignment rather than a problem you were trying to overcome yourself.

If you post up what you've got so far, what you think it should do, and what it actually does do, then people would gladly point out helpful corrections to your code. If you really are very new to Perl, you need to look at "regular expressions". If you don't have a perl book or perl installation with manpages, google search "perl regular expressions".

If you're not sure how to tackle this, someone providing you a throwaway solution without you learning anything does you no favours in the long run. Better to learn up on the general principles, have a stab at it, and then get help if your effort doesn't quite work

Have a stab at it, and post up with your results :-)