(defvar N)
(defvar A)
(defvar v)
(setq N (parse-integer (read-line)))
(setq A (read-from-string (concatenate 'string "(" (read-line) ")")))
(setq v (parse-integer (read-line)))
;(print N)
;(print A)
;(print v)

(defparameter ans 0)
(loop for x in A do
 ;(print (type-of x))
 (setq ans (+ ans x))
)
(format 't "~d~%" (- ans v))