/* -*- coding: utf-8 -*-
 *
 * 408.cc: No.408 五輪ピック - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 20000;
const int L = 5;

/* typedef */

typedef vector<int> vi;

/* global variables */

vi nbrs[MAX_N];
bool used[MAX_N];

/* subroutines */

bool rec(int u, int ul, int st) {
  vi &nbru = nbrs[u];
  int vl = ul + 1;

  for (vi::iterator vit = nbru.begin(); vit != nbru.end(); vit++) {
    int &v = *vit;
    if (v == st) {
      if (vl == L) return true;
    }
    else if (! used[v] && vl < L) {
      used[v] = true;
      if (rec(v, vl, st)) return true;
      used[v] = false;
    }
  }
  return false;
}

/* main */

int main() {
  int n, m;
  cin >> n >> m;
  for (int i = 0; i < m; i++) {
    int ai, bi;
    cin >> ai >> bi;
    ai--, bi--;
    nbrs[ai].push_back(bi);
    nbrs[bi].push_back(ai);
  }

  used[0] = true;
  bool ok = rec(0, 0, 0);

  cout << (ok ? "YES" : "NO") << endl;

  return 0;
}