This is a bit late, but is this, by chance, homework?

<Update>: (current XP == -1) Not sure what the problem is with my node:

• abbreviated writing pattern - more prevelent in the HS / College / IM crowd. If due to language barrier - my apologies up front.
• No code.
• large block of time working on a problem with an "obvious" perl solution (no offense indended to OP, but this is the stuff that perl does very well and simply).
• AM - OP is not a monk with a history.
• Class is is session
• The problem sounds very much in the vein of a question from my introductory programming courses.

So, what is the issue. If this sounds snarkey, tough. I do my work, and like to help others when they show an effort. No effort == no desire to provide help.

</Update>