#include<bits/stdc++.h>
using lint=long long;
using lubl=long double;
#define ALL(v) std::begin(v),std::end(v)
int main(){
    std::cin.tie(nullptr);std::ios_base::sync_with_stdio(false);
    std::cout.setf(std::ios_base::fixed);std::cout.precision(15);
    lint n,m;std::cin>>n>>m;
    std::vector<std::vector<lint>>g(n);
    while(m--){
        lint x,y;std::cin>>x>>y;
        g.at(x).push_back(y);
        g.at(y).push_back(x);
    }
    if(2<std::count_if(ALL(g),[](auto&&v){return v.size()%2==1u;})){
        std::cout<<"NO"<<'\n';
        return 0;
    }
    std::vector<lint>size(n),ckd(n,false),que;
    for(lint i=0,j=0;i<n;i++){
        if(std::exchange(ckd.at(i),true))continue;
        que.push_back(i);
        for(;j<(lint)que.size();j++){
            lint x=que.at(j);
            size.at(i)++;
            for(lint y:g.at(x)){
                if(std::exchange(ckd.at(y),true))continue;
                que.push_back(y);
            }
        }
    }
    std::cout<<(std::count_if(ALL(size),[](lint x){return 1<x;})<=1?"YES":"NO")<<'\n';
}