#include <bits/stdc++.h>
#define syosu(x) fixed<<setprecision(x)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef pair<double,double> pdd;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<long double> vd;
typedef vector<vd> vvd;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<string> vs;
typedef vector<P> vp;
typedef vector<vp> vvp;
typedef vector<pll> vpll;
typedef pair<int,P> pip;
typedef vector<pip> vip;
const int inf=1<<30;
const ll INF=1ll<<60;
const double pi=acos(-1);
const double eps=1e-8;
const ll mod=1e9+7;
const int dx[4]={0,1,0,-1},dy[4]={1,0,-1,0};

int n,m;
vvi g;
vi a;

void dfs(int v){
	a[v]=1;
	for(auto u:g[v]) if(!a[u]) dfs(u);
}

int main(){
	cin>>n>>m;
	g=vvi(n);
	a=vi(n);
	for(int i=0;i<m;i++){
		int u,v;
		cin>>u>>v;
		g[u].push_back(v);
		g[v].push_back(u);
	}
	int t=0,B=1;
	for(int i=0;i<n;i++) if(g[i].size()%2==1) t++;
	if(t==1||t>2) B=0;
	for(int i=0;i<n;i++) if(g[i].size()){
		dfs(i);
		break;
	}
	for(int i=0;i<n;i++) if(g[i].size()&&!a[i]) B=0;
	cout<<(B?"YES":"NO")<<endl;
}