(defun check (x y h w s)
  (let ((ss (make-array (list 101 101) :initial-element nil)))
    (dotimes (yy h)
      (dotimes (xx w)
        (unless (or (char= #\. (char (aref s yy) xx)) (aref ss yy xx))
                (setf (aref ss yy xx) t)
                (let ((yyy (+ yy y))
                      (xxx (+ xx x)))
                  (when (or (< yyy 0) (>= yyy h)
                            (< xxx 0) (>= xxx w))
                    (return-from check nil))
                  (if (and (char= #\# (char (aref s yyy) xxx))
                           (not (aref ss yyy xxx)))
                      (setf (aref ss yyy xxx) t)
                      (return-from check nil))))))
    (dotimes (yy h)
      (dotimes (xx w)
        (when (and (char= #\# (char (aref s yy) xx))
                   (not (aref ss yy xx)))
              (return-from check nil))))
    t))

(defun main (&rest argv)
  (declare (ignorable argv))
  (let* ((h (read))
         (w (read))
         (sharp-count 0)
         (s (make-array h :element-type 'string)))
    (dotimes (i h)
      (setf (aref s i) (read-line))
      (dotimes (j w)
        (when (char= #\# (char (aref s i) j))
              (incf sharp-count))))
    (when (or (oddp sharp-count) (zerop sharp-count))
          (format t "NO~%")
          (return-from main))
    (loop for x from (- w) to w do
          (loop for y from (- h) to h
                when (check x y h w s)
                  do (format t "YES~%")
                     (return-from main)))
    (format t "NO~%")))

(main)