n,m = gets.split.map(&:to_i)
x = n.times.map{[]}
m.times{
  a,b=gets.split.map(&:to_i)
  at=a
  x[a]<<b
  x[b]<<a
}

odd = x.select{|t| t.size%2==1}.size

if odd==0 || odd==2 then
  puts 'YES'
else
  puts 'NO'
end