import strutils, sequtils

var
  n, m: int
  l, r: seq[int]
  N: int
  G1, G2: seq[seq[int]]
  visited: seq[bool]
  cmp: seq[int]
  stk: seq[int]

proc nya(v: int) =
  visited[v] = true
  for vv in G1[v]:
    if visited[vv]:
      continue
    nya(vv)
  stk.add(v)

proc nyaa(v, cnt: int) =
  visited[v] = true
  for vv in G2[v]:
    if visited[vv]:
      continue
    nyaa(vv, cnt)
  cmp[v] = cnt

proc scc(): int =
  visited = newSeqWith(N, false)
  cmp = newSeqWith(N, 0)
  stk = newSeq[int](0)
  for v in 0.. <N:
    if visited[v]:
      continue
    nya(v)
  visited = newSeqWith(N, false)
  result = 0
  while len(stk) > 0:
    var v = stk.pop
    if visited[v]:
      continue
    nyaa(v, result)
    result += 1

proc rev(x: int): int = result = m-x-1

proc add_edge(v0, v1: int) =
  G1[v0].add(v1)
  G2[v1].add(v0)

proc add_edges(i, j: int) =
  add_edge(i, j)
  var
    x = if i>=n: i-n else: i+n
    y = if j>=n: j-n else: j+n
  add_edge(y, x)

###
var nm = stdin.readLine.split
n = nm[0].parseInt
m = nm[1].parseInt
l = newSeqWith(n, 0)
r = newSeqWith(n, 0)
for i in 0.. <n:
  var lr = stdin.readLine.split
  l[i] = lr[0].parseInt
  r[i] = lr[1].parseInt
N = 2 * n
G1 = newSeqWith(N, newSeq[int](0))
G2 = newSeqWith(N, newSeq[int](0))
for i in 0.. <n:
  var
    li0 = l[i]
    li1 = r[i].rev
    ri0 = r[i]
    ri1 = l[i].rev
  for j in i+1.. <n:
    var
      lj0 = l[j]
      lj1 = r[j].rev
      rj0 = r[j]
      rj1 = l[j].rev
    if li0 <= rj0 and lj0 <= ri0: add_edges(i,   n+j)
    if li1 <= rj0 and lj0 <= ri1: add_edges(n+i, n+j)
    if li0 <= rj1 and lj1 <= ri0: add_edges(i,   j  )
    if li1 <= rj1 and lj1 <= ri1: add_edges(n+i, j  )
var x = scc()
for i in 0.. <n:
  if cmp[i] == cmp[n+i]:
    echo "NO"
    quit(0)

echo "YES"