You say you've tried "everything possible", so just pick the one that gave you the correct solution. ;^)

Seriously, show the code that you've tried. I'm sure someone can (and probably will) just give you the answer, but it's more satisfying to help someone fix their code, rather than handing you the answer. Once you put up some code, someone will be sure to give you a hand finding out where you have difficulties.

I've recently played with YAPE::Regex::Explain, and if you try it out, you can tweak your regular expressions and have it tell you what it will do. That's a pretty good way to see where you're going wrong.

I'm assuming that you've already read perldoc perlre, so I won't bother mentioning it.

...roboticus

When your only tool is a hammer, all problems look like your thumb.

Update: Repaired CPAN link, thanks to toolic and atcroft for the catch!