; variables

; k: the number of beans in a pack
; n: the number of packs
; f: the number of family members
; (k n f)
(defparameter *bean-pack-family* ())
(defparameter *input-str* nil)
(defparameter *num-list* ())
(defparameter *age-list* ())
(defvar *num-stack* ())
(defvar *list-stack* ())


; function

(defun separate-n (c)
  (cond
    ((char= c #\ )
     (push (parse-integer (coerce (reverse *num-stack*) 'string)) *list-stack*)
     (setf *num-stack* '())
     )
    (t
      (push c *num-stack*)))
  )

(defun str-to-int-list (str)
  (map nil #'separate-n str) 
  (push (parse-integer (coerce (reverse *num-stack*) 'string)) *list-stack*)
  (reverse *list-stack*)
  )

(defun input-to-list ()
  (setf *input-str* (read-line))
  (setf *num-list* (str-to-int-list *input-str*))
  (reset-stack)
  )

(defun reset-stack ()
  (setf *num-stack* ())
  (setf *list-stack* ())
  )

(defun input-to-age ()
  (setf *input-str* (read-line))
  (setf *age-list* (str-to-int-list *input-str*))
  )

(defun eat-bean (total age-list)
  (cond
    ((< total 0) -1)
    ((< (length age-list) 1)
     total)
    (t 
      (eat-bean (- total (car age-list)) (cdr age-list))))
  )

(defun n143 ()
  (input-to-list)
  (input-to-age)
  (princ (eat-bean (* (car *num-list*) (cadr *num-list*))
		   *age-list*))
  )

(n143)