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

using ll = long long;
#define rep(i, j) for(int i=0; i < (int)(j); i++)
#define repeat(i, j, k) for(int i = (j); i < (int)(k); i++)
#define all(v) v.begin(),v.end()

template<class T> istream& operator >> (istream &is , vector<T> &v) { for(T &a : v) is >> a; return is; }

class Solver {
  public:
    vector<vector<int>> E;
    bool dfs(int dep, int now, set<int> &visited, int start) {
        if(dep == 5 and now == start) return true;
        if(dep >= 5) return false;
        if(visited.count(now)) return false;
        bool flg = false;
        visited.insert(now);
        for(int nxt : E[now]) {            
            flg |= dfs(dep + 1, nxt, visited, start);
        }
        visited.erase(now);
        return flg;
    }
    
    bool solve() {
        int N, M; cin >> N >> M;
        E.resize(N);
        rep(i, M) {
            int a, b; cin >> a >> b;
            a--, b--;
            E[a].push_back(b);
            E[b].push_back(a);
        }
        bool flg = false;
        set<int> visited;
        cout << (dfs(0, 0, visited, 0) ? "YES" : "NO") << endl;
        
        return 0;
    }
};

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    Solver s;
    s.solve();
    return 0;
}