(defun main (&rest argv)
  (declare (ignorable argv))
  (let* ((n (read))
         (m (read))
         (a 0)
         (b 0)
         (flg t))
    (declare (ignore n))
    (dotimes (_ m)
      (let* ((p (read))
             (q (read)))
        (when (< (abs (- a p)) (abs (- b q)))
              (setq flg nil))
        (setq a p
              b q)))
    (format t "~a~%" (if flg "Yes" "No"))))

(main)