n,m=gets.split(" ").map(&:to_i)
cnt=Array.new(n,0)
@edge=Array.new(n){[]}
m.times{
    a,b=gets.split(" ").map(&:to_i)
    cnt[a]^=1
    cnt[b]^=1
    @edge[a].<<b
    @edge[b].<<a
}
@visit=Array.new(n,false)
def dfs(i)
    @visit[i]=true
    for j in @edge[i] do
        if !@visit[j] then
            dfs(j)
        end
    end
end
def check()
    for i in 0...@edge.length do
        if @edge[i]!=[]&&@visit[i]==false then
            return false
        end
    end
    return true
end
dfs(0)
if check()&&[0,2].include?(cnt.count(1)) then
    puts "YES"
else
    puts "NO"
end