(defun main (&rest argv)
  (declare (ignorable argv))
  (let* ((s (read))
         (a (read))
         (b (read))
         (c (floor (* a b) (gcd a b)))
         (res (- (+ (floor s a) (floor s b)) (floor s c))))
    (unless (zerop (mod s a)) (incf res))
    (unless (zerop (mod s b)) (incf res))
    (unless (zerop (mod s c)) (decf res))
    (format t "~d~%" res)))

(main)