((?>[^()]+)|\([^()]*\))+ ((abc(ade)ufh()()x y $& abc(ade)ufh()()x
(?<=x+)y - c - Variable length lookbehind not implemented
a{37,17} - c - Can't do {n,m} with n > m
+a{37,0} - c - Can't do {n,m} with n > m
\Z a\nb\n y $-[0] 3
\z a\nb\n y $-[0] 4
$ a\nb\n y $-[0] 3