#include <cstdio>
#include <cstring>
#include <string>
#include <cmath>
#include <cassert>
#include <iostream>
#include <algorithm>
#include <stack>
#include <queue>
#include <vector>
#include <set>
#include <map>
#include <bitset>
using namespace std;

#define repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repl(i,0,n)
#define mp(a,b) make_pair(a,b)
#define pb(a) push_back(a)
#define all(x) (x).begin(),(x).end()
#define dbg(x) cout<<#x"="<<x<<endl
#define fi first
#define se second

#define INF 2147483600

#define N 20000
#define M 50000
typedef pair<int, int> P;
vector<int> g[N];
vector<int> len2[N];
P edg[M];

int main(){
  int n,m;
  cin>>n>>m;
  rep(i,m){
    int a,b;
    scanf("%d %d", &a, &b);
    a--;b--;
    g[a].pb(b);
    g[b].pb(a);
    edg[i]=mp(a,b);
  }

  rep(i, g[0].size()){
    int mid = g[0][i];
    rep(j, g[mid].size()){
      int tgt = g[mid][j];
      // 0->mid->tgt
      if(tgt==0) continue;
      len2[tgt].pb(mid);
    }
  }

  rep(i, m){
    int a = edg[i].fi, b = edg[i].se;
    if(len2[a].size()>=3 && len2[b].size()>=3){
      cout<<"YES"<<endl;
      return 0;
    }
    for(auto ai : len2[a]) for(auto bi : len2[b]){
      if(ai!=bi && ai!=b && bi!=a){ cout<<"YES"<<endl; return 0;}
    }
  }

  cout<<"NO"<<endl;

  return 0;
}