(defvar *prog-input*)

(let ((ui (read-line)))
  (if (equal ui "")
    (setq *prog-input* *standard-input*)
    (setq *prog-input* (open ui))))

(let
  ((cal (read-line *prog-input* NIL)) (maxsum 0) (csum 0))

  (loop until (or (equal cal "end") (not cal)) do
    (if (equal cal "")
      (setq csum 0)
      (setq csum (+ csum (parse-integer cal))))
    (if (> csum maxsum)
      (setq maxsum csum))
    (setq cal (read-line *prog-input* NIL)))

  (print maxsum))

(if (not (eq *prog-input* *standard-input*))
  (close *prog-input*))