use warnings;
use strict;

my $m = (1 << 15) + 1;   # 32769
my $_="#\n" . "A\n" x $m . "#\n";
	s/
	^[^#].*?$		# find a line which haven't "#" at it beginning.
	(?:\n[^#].*?$)*	# find consecutive n (n>=0) such lines
	/
		$a=$&,
		$a=~y{\n}{}d,  # delete newlines
		$a
	/megx ;           ## multiline, eval, global, comments
my $n = () = /\n/sg;	# calc the number of occurences of "\n"
print $n

# ANSWER: 4, My expectation was: 3