N, M = gets.split.map(&:to_i)
E = Hash.new { |h, k| h[k] = [] }

M.times do
  a, b = gets.split.map(&:to_i)
  E[a] << b
  E[b] << a
end

def f
  E.all? { |u, list| list.size.even? }
end

def g
  odd_cnt = 0
  even_cnt = 0

  E.each do |u, list|
    if list.size.even?
      even_cnt += 1
    else
      odd_cnt += 1
    end
  end

  odd_cnt == 2
end

if f || g
  puts 'YES'
else
  puts 'NO'
end