;; -*- 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 15) (*)))
  ;; the total number of strongly connected components
  (count 0 :type (unsigned-byte 15)))

(declaim (inline %make-revgraph))
(defun %make-revgraph (graph)
  (let* ((n (length graph))
         (revgraph (make-array n :element-type 'list :initial-element nil)))
    (dotimes (i n)
      (dolist (dest (aref graph i))
        (push i (aref revgraph dest))))
    revgraph))

(defun make-scc (graph &optional revgraph)
  "GRAPH := vector of adjacency lists
REVGRAPH := NIL | reversed graph of GRAPH"
  (declare #.OPT
           ((simple-array list (*)) graph)
           ((or null (simple-array list (*))) revgraph))
  (let* ((revgraph (or revgraph (%make-revgraph graph)))
         (n (length graph))
         (visited (make-array n :element-type 'bit :initial-element 0))
         (posts (make-array n :element-type '(unsigned-byte 15)))
         (components (make-array n :element-type '(unsigned-byte 15)))
         (pointer 0)
         (ord 0) ; ordinal number for a strongly connected component
         )
    (declare ((unsigned-byte 15) 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))
    (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)))
               (push literal2 (aref graph (negate literal1)))
               (push literal1 (aref graph (negate literal2)))))
      (declare (inline negate overlap-p))
      (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))
             (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)