use warnings;
use strict;

# the width and height of the torus ...
my ($w, $h) = (10, 10);

# initializing the universe as empty ...
@_ = map { 0 } (1..$w*$h);

# defining some patterns ...
$_[16] =
$_[16+$w-1] =
$_[16+$w-1+$w] =
$_[16+$w-1+$w+1] =
$_[16+$w-1+$w+1+1] =
1;

# printing the current state of the universe (torus) ...
sub p {
	map { print "\n" } (1..24-$h);
	map { $, = $_[$_] ? '*' : '.'; ($_+1)%$w ? print $, : print "$,\n" } (0..$#_)
}

# getting (the indexes of) the neighbours of a cell ...
sub n {
	($w*$h+$.-$w)%($w*$h)		# N
	, ($.+$w)%($w*$h)		# S
	, ($.%$w+1)%$w+$.-($.%$w)	# E
	, ($.%$w+$w-1)%$w+$.-($.%$w)	# W
	, ((($w*$h+$.-$w)%($w*$h))%$w+$w-1)%$w+(($w*$h+$.-$w)%($w*$h))-((($w*$h+$.-$w)%($w*$h))%$w)	# NW
	, ((($.+$w)%($w*$h))%$w+1)%$w+(($.+$w)%($w*$h))-((($.+$w)%($w*$h))%$w)				# SE
	, ((($.+$w)%($w*$h))%$w+$w-1)%$w+(($.+$w)%($w*$h))-((($.+$w)%($w*$h))%$w)			# SW
	, ((($w*$h+$.-$w)%($w*$h))%$w+1)%$w+(($w*$h+$.-$w)%($w*$h))-((($w*$h+$.-$w)%($w*$h))%$w)	# NE
}

# the rules of the universe ...
sub r {
	$,=0;
	map { $,+=$_[$_] } &n; 
	$_[$.] ? ($,==2||$,==3?1:0) : ($,==3?1:0)
}

my @w;

# one generation of the universe ...
sub l {
	for $. (0..$#_) {
		$w[$.] = &r
	}
	@_ = @w
}

# the life ...
while (1) {
	&p;
	&l;
	sleep 1
}