(defun c (lst floor count)
(cond
((= floor -1)
(1- count))
((null lst)
(1- count))
((char= (car lst) #\()
(c (cdr lst) (1+ floor) (1+ count)))
((char= (car lst) #\))
(c (cdr lst) (1- floor) (1+ count)))
(t
(1- count))))
(defun solve ()
(labels ((inner ()
(let ((count (c (concatenate 'list (read-line)) 0 1)))
(format t "~a~%" count)
(inner))))
(handler-case
(inner)
(end-of-file () nil))))
(solve)
Note that non-ascii characters in the above source code will be escaped (such as \x9f).