use strict;
use warnings;
use Data::Dumper;

my %lights;

$lights{$_} = 0 for (1..4);
foreach my $light ( sort { $a <=> $b } (keys %lights) ){
		foreach my $divisor ( 2..4 ) {
			if ( $light % $divisor == 0 ) { # if it divides evenly, pull the cord
				if ( $lights{$light} ) {
					$lights{$light} = 0;
				} else {
					$lights{$light} = 1;
				} 
			}
		}
}
report({%lights}); # outputs 1 4

$lights{$_} = 0 for (1..4);
foreach my $light ( sort { $a <=> $b } (keys %lights) ){
		foreach my $divisor ( 2..4 ) {
			if ( $light % $divisor == 0 ) { # if it divides evenly, pull the cord
				$lights{$light} ? $lights{$light} = 0 : $lights{$light} = 1; # turn off if it's on, and vice versa.
			}
		}
}
report({%lights}); #outputs 1


sub report {
	my $lights = shift;
	print "off lights: ";
	foreach (sort { $a <=> $b }( keys %{$lights} ) ) {
			print "$_ " unless $lights->{$_}; 
	}
	print "\n";
}