#include<bits/stdc++.h>
using namespace std;
using Int = long long;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}


struct UnionFind{
  int n;
  vector<int> r,p;
  UnionFind(){}
  UnionFind(int sz):n(sz),r(sz,1),p(sz,0){iota(p.begin(),p.end(),0);}
  int find(int x){
    return (x==p[x]?x:p[x]=find(p[x]));
  }
  bool same(int x,int y){
    return find(x)==find(y);
  }
  void unite(int x,int y){
    x=find(x);y=find(y);
    if(x==y) return;
    if(r[x]<r[y]) swap(x,y);
    r[x]+=r[y];
    p[y]=x;
  }
  int size(int x){
    return r[find(x)];
  }
};

//INSERT ABOVE HERE
signed main(){
  int n,m;
  cin>>n>>m;
  UnionFind uf(n);
  vector<int> deg(n);
  for(int i=0;i<m;i++){
    int a,b;
    cin>>a>>b;
    deg[a]++;deg[b]++;
    uf.unite(a,b);
  }
  int cnt=0,num=0;
  for(int i=0;i<n;i++){
    if(deg[i]&1) num++;
    if(uf.find(i)!=i) continue;
    if(uf.size(i)==1) continue;
    cnt++;
  }
  cout<<(cnt==1&&num<=2?"YES":"NO")<<endl;
  return 0;
}