Add

use strict;
use warnings;
[download]

To the top of your program and correct your errors accordingly.
Also: don't manipulate the default list (@_) in a procedure. Assign its values to local (my, not our) variables and use those; and at any rate, referring to a specific variable in a list is done through $list[0], not @list[0]. As it is, there are so many ways why it *shouldn't* work, than suggestions how to make it work properly.