n,m=gets.split(" ").map(&:to_i)
cnt=Array.new(n,0)
m.times{
    a,b=gets.split(" ").map(&:to_i)
    cnt[a]^=1
    cnt[b]^=1
}
if cnt.count(1)<=2 then
    puts "YES"
else
    puts "NO"
end