#!/usr/bin/perl

# http://perlmonks.org/?node_id=1121552

use strict;
use warnings;

for my $y ( 1..25 )
  {
  local $_ = tile(5,$y);
  /1$/ and !/-/ and print "success  5,$y\n";
  }

sub tile
  {
  my ($w, $h) = @_;
  my $wm1 = $w - 1;
  local $_ = ( '-' x $w . "\n" ) x $h;
  s/-/1/;
  1 while  # print("$_\n"),
    s/1..{$w}\K-/1/s ||
    s/1\n.*\K-(?=\n)/2/ ||
    s/1(?=.*$)\K-/4/ ||
    s/2.{$wm1}\K-/2/s ||
    s/2.{$wm1}\n\K-/1/ ||
    s/-(?=2.*$)/3/ ||
    s/-(?=..{$w}3)/3/s ||
    s/^.*\K-(?=3)/2/ ||
    s/-(?=.{$wm1}\n3)/4/ ||
    s/-(?=.{$wm1}4)/4/s ||
    s/^.*4\K-/1/ ||
    s/-(?=.{$w}4\n)/3/s;

  return $_;
  }