if ($expire < 1 ||  14 < $expire || int $expire != $expire) { die "Don't tamper with me!"; }

##</code><code>##

my %check;
undef @check{1..14};

if (! exists $check{$expire}) { die "Don't tamper with me!"; }

##</code><code>##

if ($expire !~ /^(?:[1-9]|1[0-4])$/) { die "Don't tamper with me!"; }

##</code><code>##

use Quantum::Superpositions;

if ($expire != any(1..14)) { die "Don't tamper with me!"; }