#!/usr/bin/perl -w
use strict;

package First;
  # set the symbol: MULTIPLIER 
  # and make $x equal to its value.
use constant MULTIPLIER => 5*5;
my $x = MULTIPLIER;

package Second;
  # set a new symbol: if $x is defined in this context,
  # make this MULTIPLIER the same as the first,
  # otherwise "2".
use constant MULTIPLIER => defined $x ? First::MULTIPLIER : 2;
  # easy! It's an error...it's 265...it's 50?  Find out :-)
print MULTIPLIER * $x, "\n";