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

(setq x (read-from-string (concatenate 'string "(" (read-line) ")")))

(defvar s)
(setq s 0)
(loop for i in x do
 	(setq s (+ s i))
)
(format t "~a~%" (if (= (* a n) s) "YES" "NO"))