(defun main (&rest argv)
  (declare (ignorable argv))
  (let* ((aw (read))
         (ab (read))
         (bw (read))
         (bb (read))
         (c (read))
         (d (read))
         (res (- (+ aw (min (+ bw (max 0 (- c ab))) d)) (max 0 (- c ab)))))
    (declare (ignore bb))
    (format t "~d~%" res)))

(main)