pc88mxer has given you the pointers to solve your problem and BrowserUk an alternative, but in future you will find the Monks more receptive and more inclined to help if:-

You show some initiative on your part by posting what you have tried. It does not matter that it is not a complete solution to the entire problem or only a part.

Nor does it matter that it does not work nor even that you feel it is the totally wrong approach.

That you have at least tried to find a solution yourself shows some commitment on your part, that you have come here to learn Perl and that you do not want just a quick fix for your Homework.