(defparameter *mod* 1000000007)

(defun fact (x)
  (if (zerop x)
      1
      (* x (fact (1- x)))))

(defun main ()
  (let ((n (read)))
    (let ((a (loop repeat n collect (read))))
      (labels ((sub (xs &optional (res 1))
                 (cond
                   ((null xs) (mod *mod* res))
                   ((> res *mod*) -1)
                   (t
                    (sub (rest xs) (* (expt (first xs)
                                            (fact (first xs)))
                                      res))))))
        (princ (if (some #'zerop a)
                   -1
                   (if (every (lambda (x)
                                (<= 1 x 3))
                              a)
                       (sub a)
                       -1)))))))
(main)