for (my $y = 1; $y <= $q; $y++) {
    for (my $x = 1; $x <= $p; $x++) {
      for (my $ny=$y-1; $ny<=$y+1; $ny++) {
        next if ($ny < 1 || $ny > $q);
        for (my $nx=$x-1; $nx<=$x+1; $nx++) {
          next if ($nx < 1 || $nx > $p || ($nx == $x && $ny == $y));
          push @{$adjlist{"$x,$y"}}, [$nx,$ny];
        }
      }
    }
  }