N, M = gets.split.map(&:to_i)
Q = M.times.map { gets.split.map(&:to_i) }

time = 0
cur = 0

Q.each do |t, q|
  limit = (cur - q).abs

  if t - time < limit
    puts 'No'
    exit
  end

  cur = q
  time = t
end

puts 'Yes'