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
}