(defvar W)
(defvar D)
(setq W (parse-integer (read-line)))
(setq D (parse-integer (read-line)))

(defvar work)
(setq work (floor W (* D D)))
(loop while (> W work) do
      (setq D (- D 1))
      (setq W (- W work))
      (setq work (floor W (* D D)))
;      (format t "<~d>~%" W)
;      (format t "<~d>~%" work)
)
(format t "~d~%" work)