#include <bits/stdc++.h>

using namespace std;

#define fst(t) std::get<0>(t)
#define snd(t) std::get<1>(t)
#define thd(t) std::get<2>(t)

using ll = long long;
using P = std::tuple<int,int>;

const int dx[8] = {-1, 1, 0, 0, -1, -1, 1, 1}, dy[8] = {0, 0, -1, 1, -1, 1, -1, 1};

int N, M;
vector<int> G[20000];
bool used[20000];

int can(int u, int n){
    bool f = false;
    for(int v : G[u]){
        if(v == 0 && n == 5){return true;}

        if(!used[v]){
            used[v] = true;
            // std::cout << "-> " << v << std::endl;
            f = f || can(v, n + 1);
        }
    }

    return f;
}

int main(){
    //*
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);
    /*/
      /*/

    std::cin >> N >> M;

    for(int i=0;i<M;++i){
        int A, B;
        std::cin >> A >> B;

        --A; --B;

        G[A].emplace_back(B);
        G[B].emplace_back(A);
    }

    used[0] = true;
    bool f = can(0, 1);

    if(f){
        std::cout << "YES" << std::endl;
    }else{
        std::cout << "NO" << std::endl;
    }
}