;; -*- coding: utf-8 -*-
(eval-when (:compile-toplevel :load-toplevel :execute)
  (sb-int:defconstant-eqx OPT
    #+swank '(optimize (speed 3) (safety 2))
    #-swank '(optimize (speed 3) (safety 0) (debug 0))
    #'equal)
  #+swank (ql:quickload '(:cl-debug-print :fiveam) :silent t)
  #-swank (set-dispatch-macro-character
           #\# #\> (lambda (s c p) (declare (ignore c p)) (read s nil nil t))))
#+swank (cl-syntax:use-syntax cl-debug-print:debug-print-syntax)
#-swank (disable-debugger) ; for CS Academy

;; BEGIN_INSERTED_CONTENTS
(defmacro define-int-types (&rest bits)
  `(progn
     ,@(mapcar (lambda (b) `(deftype ,(intern (format nil "UINT~A" b)) () '(unsigned-byte ,b))) bits)
     ,@(mapcar (lambda (b) `(deftype ,(intern (format nil "INT~A" b)) () '(signed-byte ,b))) bits)))
(define-int-types 2 4 7 8 15 16 31 32 62 63 64)

(declaim (ftype (function * (values fixnum &optional)) read-fixnum))
(defun read-fixnum (&optional (in *standard-input*))
  (declare #.OPT)
  (macrolet ((%read-byte ()
               `(the (unsigned-byte 8)
                     #+swank (char-code (read-char in nil #\Nul))
                     #-swank (sb-impl::ansi-stream-read-byte in nil #.(char-code #\Nul) nil))))
    (let* ((minus nil)
           (result (loop (let ((byte (%read-byte)))
                           (cond ((<= 48 byte 57)
                                  (return (- byte 48)))
                                 ((zerop byte) ; #\Nul
                                  (error "Read EOF or #\Nul."))
                                 ((= byte #.(char-code #\-))
                                  (setf minus t)))))))
      (declare ((integer 0 #.most-positive-fixnum) result))
      (loop
        (let* ((byte (%read-byte)))
          (if (<= 48 byte 57)
              (setq result (+ (- byte 48)
                              (* 10 (the (integer 0 #.(floor most-positive-fixnum 10)) result))))
              (return (if minus (- result) result))))))))

;;;
;;; Strongly connected components of directed graph
;;;

(defstruct (scc (:constructor %make-scc (graph revgraph posts components count)))
  (graph nil :type (simple-array list (*)))
  ;; reversed graph
  (revgraph nil :type (simple-array list (*)))
  ;; vertices by post-order DFS
  posts
  ;; components[i] := strongly connected component of the i-th vertex
  (components nil :type (simple-array (unsigned-byte 32) (*)))
  ;; the total number of strongly connected components
  (count 0 :type (unsigned-byte 32)))


(defun make-scc (graph revgraph)
  "GRAPH, REVGRAPH := vector of adjacency lists"
  (declare #.OPT
           ((simple-array list (*)) graph revgraph))
  (let* ((n (length graph))
         (visited (make-array n :element-type 'bit :initial-element 0))
         (posts (make-array n :element-type '(unsigned-byte 32)))
         (components (make-array n :element-type '(unsigned-byte 32)))
         (pointer 0)
         (ord 0) ; ordinal number for a strongly connected component
         )
    (declare ((unsigned-byte 32) pointer ord))
    (assert (= n (length revgraph)))
    (labels ((dfs (v)
               (setf (aref visited v) 1)
               (dolist (neighbor (aref graph v))
                 (when (zerop (aref visited neighbor))
                   (dfs neighbor)))
               (setf (aref posts pointer) v)
               (incf pointer))
             (reversed-dfs (v ord)
               (setf (aref visited v) 1
                     (aref components v) ord)
               (dolist (neighbor (aref revgraph v))
                 (when (zerop (aref visited neighbor))
                   (reversed-dfs neighbor ord)))))
      (dotimes (v n)
        (when (zerop (aref visited v))
          (dfs v)))
      (fill visited 0)
      (loop for i from (- n 1) downto 0
            for v = (aref posts i)
            when (zerop (aref visited v))
            do (reversed-dfs v ord)
               (incf ord))
      (%make-scc graph revgraph posts components ord))))

(defmacro dbg (&rest forms)
  #+swank
  (if (= (length forms) 1)
      `(format *error-output* "~A => ~A~%" ',(car forms) ,(car forms))
      `(format *error-output* "~A => ~A~%" ',forms `(,,@forms)))
  #-swank (declare (ignore forms)))

(declaim (inline println))
(defun println (obj &optional (stream *standard-output*))
  (let ((*read-default-float-format* 'double-float))
    (prog1 (princ obj stream) (terpri stream))))

(defconstant +mod+ 1000000007)

;;;
;;; Body
;;;

(defun main ()
  (declare #.OPT)
  (let* ((n (read))
         (m (read))
         (ls (make-array (* 2 n) :element-type 'uint16))
         (rs (make-array (* 2 n) :element-type 'uint16))
         (graph (make-array (* 4 n) :element-type 'list :initial-element nil))
         (revgraph (make-array (* 4 n) :element-type 'list :initial-element nil))
         (4n (* 4 n)))
    (declare (uint16 n m 4n))
    (dotimes (i n)
      (let* ((l (read-fixnum))
             (r (read-fixnum)))
        (declare (uint16 l r))
        (setf (aref ls i) l
              (aref rs i) r
              (aref ls (+ i n)) (- m r 1)
              (aref rs (+ i n)) (- m l 1))))
    (labels ((overlap-p (x y)
               (let ((l1 (aref ls x))
                     (r1 (aref rs x))
                     (l2 (aref ls y))
                     (r2 (aref rs y)))
                 (not (or (< r1 l2) (< r2 l1)))))
             (negate (x)
               (declare (uint16 x))
               (let ((res (+ x (* 2 n))))
                 (if (>= res 4n)
                     (- res 4n)
                     res)))
             (add-clause! (literal1 literal2 bool1 bool2)
               (unless bool1
                 (setq literal1 (negate literal1)))
               (unless bool2
                 (setq literal2 (negate literal2)))
               (let ((neg1 (negate literal1))
                     (neg2 (negate literal2)))
                 (push literal2 (aref graph neg1))
                 (push neg1 (aref revgraph literal2))
                 (push literal1 (aref graph neg2))
                 (push neg2 (aref revgraph literal1)))))
      (declare (inline negate))
      (gc :full t)
      (dotimes (x (* 2 n))
        (loop for y from (+ x 1) below (* 2 n)
              do (when (and (/= (+ x n) y)
                            (overlap-p x y))
                   (add-clause! x y nil nil))))
      (dotimes (x n)
        (add-clause! x (+ x n) t t)
        (add-clause! x (+ x n) nil nil))
      (let* ((scc (make-scc graph revgraph))
             (comps (scc-components scc)))
        (write-line
         (if (loop for x below (* 2 n)
                   thereis (= (aref comps x)
                              (aref comps (+ x (* 2 n)))))
             "NO"
             "YES"))))))

#-swank (main)