(defun main (&rest argv)
  (declare (ignorable argv))
  (let* ((w (read))
         (h (read))
         (n (read))
         (s (make-hash-table))
         (k (make-hash-table)))
    (dotimes (i n)
      (let* ((a (read))
             (b (read)))
        (setf (gethash a s) t)
        (setf (gethash b k) t)))
    (let* ((cnt-s (hash-table-count s))
           (cnt-k (hash-table-count k))
           (res (- (+ (* cnt-s h) (* cnt-k w)) (* cnt-s cnt-k) n)))
      (format t "~d~%" res))))

(main)