#include <bits/stdc++.h>
using namespace std;

int main(){
  int n,m;
  cin>>n>>m;
  vector<int>from(m),to(m);
  unordered_set<long long> s;
  vector<int>adj;
  for(int i=0;i<m;i++){
    cin>>from[i]>>to[i];
    from[i]--;to[i]--;
    if(from[i]==0)adj.emplace_back(to[i]);
    if(to[i]==0)adj.emplace_back(from[i]);
    s.emplace(from[i]*100000+to[i]);
    s.emplace(to[i]*100000+from[i]);
  }
  for(int i=0;i<m;i++){
    if(from[i]==0)continue;
    if(to[i]==0)continue;
    int a=0,b=0,c=0;
    for(auto& j:adj){
      if(j==from[i])continue;
      if(j==to[i])continue;
      if(!s.count(j))continue;
      int x=0;
      if(s.count(j*100000+from[i]))x|=1;
      if(s.count(j*100000+to[i]))x|=2;
      if(x==1)a++;
      else if(x==2)b++;
      else if(x==3)c++;
      if((a>0&&b>0)||(a>0&&c>0)||(b>0&&c>0)||(c>=2)){
        cout<<"YES"<<endl;
        return 0;
      }

    }
  }
  cout<<"NO"<<endl;
}