#include <bits/stdc++.h>

using namespace std;

struct Edge {
    int a, b;
    Edge(int a, int b) : a(a), b(b) {}
    bool operator<(const Edge& e) const {
        return a == e.a ? b < e.b : a < e.a;
    }
};

int main() {
    int N, M;
    scanf("%d %d\n", &N, &M);
    set<Edge> es;
    vector<Edge> es1;
    vector<int> zero_n;
    for (int i = 0; i < M; i++) {
        int a, b;
        scanf("%d %d\n", &a, &b);
        a--; b--;
        if (a > b) swap(a, b);
        if (a == 0) zero_n.push_back(b);
        else es1.emplace_back(a, b);
        es.emplace(a, b);
    }

    auto f = [&](int a, int b) {
        if (a > b) swap(a, b);
        return es.count(Edge(a, b));
    };

    for (auto e : es1) {
        bool a = false, b = false;
        int c = 0;
        for (auto i : zero_n) {
            if (i == e.a || i == e.b) continue;
            bool flag = false;
            if (f(e.a, i)) {
                a = true;
                flag =true;
            }
            if (f(e.b, i)) {
                b = true;
                flag = true;
            }
            c += flag;
        }
        if (c >= 2 && a && b) {
            cout << "YES" << endl;
            return 0;
        }
    }
    cout << "NO" << endl;

}