;; -*- 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)

;;;
;;; Disjoint set by Union-Find algorithm
;;;

(defstruct (disjoint-set
            (:constructor make-disjoint-set
                (size &aux (data (make-array size :element-type 'int32 :initial-element -1))))
            (:conc-name ds-))
  (data nil :type (simple-array int32 (*))))

(declaim (ftype (function * (values (mod #.array-total-size-limit) &optional)) ds-root))
(defun ds-root (x disjoint-set)
  "Returns the root of X."
  (declare #.OPT
           ((mod #.array-total-size-limit) x))
  (let ((data (ds-data disjoint-set)))
    (if (< (aref data x) 0)
        x
        (setf (aref data x)
              (ds-root (aref data x) disjoint-set)))))

(declaim (inline ds-unite!))
(defun ds-unite! (x1 x2 disjoint-set)
  "Destructively unites X1 and X2 and returns true iff X1 and X2 become
connected for the first time."
  (let ((root1 (ds-root x1 disjoint-set))
        (root2 (ds-root x2 disjoint-set)))
    (unless (= root1 root2)
      (let ((data (ds-data disjoint-set)))
        ;; ensure the size of root1 >= the size of root2
        (when (> (aref data root1) (aref data root2))
          (rotatef root1 root2))
        (incf (aref data root1) (aref data root2))
        (setf (aref data root2) root1)))))

(declaim (inline ds-connected-p))
(defun ds-connected-p (x1 x2 disjoint-set)
  "Returns true iff X1 and X2 have the same root."
  (= (ds-root x1 disjoint-set) (ds-root x2 disjoint-set)))

(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 sizes 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) (*)))
  ;; sizes[k] := size of the k-th strongly connected component
  (sizes nil :type (simple-array (unsigned-byte 32) (*)))
  ;; the total number of strongly connected components
  (count 0 :type (unsigned-byte 32)))

(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 32)))
         (components (make-array n :element-type '(unsigned-byte 32)))
         (sizes (make-array n :element-type '(unsigned-byte 32)
                            :initial-element 0))
         (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)
               (incf (aref sizes 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 sizes 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))
         (dset (make-disjoint-set (+ n n m)))
         (graph (make-array (* 4 n) :element-type 'list :initial-element nil)))
    (declare (uint16 n m))
    (dotimes (i n)
      (let* ((l (read-fixnum))
             (r (read-fixnum)))
        (loop for j from l to r
              do (ds-unite! i (+ j (* 2 n)) dset))
        (loop for j from (- m r 1) to (- m l 1)
              do (ds-unite! (+ i n) (+ j (* 2 n)) dset))))
    (labels ((negate (x)
               (declare (uint16 x))
               (mod (+ x (* 2 n)) (* 4 n)))
             (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)))))
      (gc :full t)
      (dotimes (x (* 2 n))
        (loop for y from (+ x 1) below (* 2 n)
              do (when (ds-connected-p x y dset)
                   (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)