Hello, thanos1983. There's a more or less unspoken consensus on this kind of questions, where the author seems to expect the job to be done without any effort on their part, is to never provide a fully functional answer, but at most pieces of solutions, through documentation or small solutions to sub problems.

That's not the first post from pdahal with a clear lack of effort. Actually the title from this nodes reminded me of Backtracking in perl, where it kind of looks like the OP tried pretty much the same approach, but by replacing "back" by "forward", just in case it would fool us into giving the answer. So this might have played a role on the number of downvotes you got (which would be infortunate, you're not supposed to know the posting history of the monks you answer to)

NB: There was a discussion a few days ago on a closely related subject here.

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.