print "a\n\nc\n" =~ / a\n ^ $    c\n /mx ?1:0, "\n";  # 0
print "a\n\nc\n" =~ / a\n ^ $ \n c\n /mx ?1:0, "\n";  # 1

##</code><code>##

$_ = "abc\n"
   . "def\n"
   . "\n"
   . "jkl\n"
   . "\n"
   . "\n"
   . "stu\n";

s/^\n//mg;
print;

##</code><code>##

abc
def
jkl
stu