(defvar a)
(defvar b)
(defvar temp)
(setq temp (read-from-string (concatenate 'string "(" (read-line) ")" )))
(setq a (nth 0 temp))
(setq b (nth 1 temp))

(setq temp (- b a))
(format t (concatenate 'string (if (> temp 0 ) "+" ) "~d~%" ) temp)