(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))))
      (princ (if (some #'zerop a)
                 -1
                 (if (every (lambda (x)
                              (<= 1 x 3))
                            a)
                     (mod *mod* (reduce #'*
                                        (mapcar (lambda (x)
                                                  (expt x (fact x)))
                                                a)))
                     0))))))
(main)