(defconstant +mod107+ 1000000007)

(defun main (&rest argv)
  (declare (ignorable argv))
  (let* ((n (read))
         (a (make-array 100 :element-type 'integer)))
    (dotimes (i n) (setf (aref a i) (read)))
    (dotimes (i (1- n))
      (dotimes (j (- n 1 i))
        (setf (aref a j) (mod (+ (aref a j) (aref a (1+ j))) +mod107+))))
    (format t "~d~%" (aref a 0))))

(main)