n, m = read_line.split.map &.to_i
cnt = [0] * (m.succ // 2)
n.times do
  l, r = read_line.split.map &.to_i
  (l..r).each do |i|
    cnt[i < cnt.size ? i : cnt.size - i - 1] += 1
  end
end
puts cnt.all? {|i| i <= 2 } ? "YES" : "NO"