#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;
    }
};
namespace std {
    template<> struct hash<Edge> {
        size_t operator()(const Edge& e) const {
            return size_t((e.a << 15) ^ e.b);
        }
    };
}

const int INF = 1<<28;

int main() {
    int N, M;
    scanf("%d %d\n", &N, &M);
    unordered_set<Edge> es;
    vector<Edge> es1;
    vector<vector<int>> G(N);
    vector<bool> zero_n(N, false);
    for (int i = 0; i < M; i++) {
        int a, b;
        scanf("%d %d\n", &a, &b);
        a--; b--;
        G[a].push_back(b);
        G[b].push_back(a);
        if (a > b) swap(a, b);
        if (a == 0) zero_n[b] = true;
        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) {
        int a = -1, b = -1;
        int c = 0;
        for (auto i : G[e.a]) {
            if (!zero_n[i]) continue;
            if (i == e.b) continue;
            if (f(e.a, i)) {
                if (a < 0) a = i;
                else a = INF;
            }
        }
        if (a < 0) continue;
        for (auto i : G[e.b]) {
            if (!zero_n[i]) continue;
            if (i == e.a) continue;
            if (f(e.b, i)) {
                if (b < 0) b = i;
                else b = INF;
            }
        }

        if (a >= 0 && b >= 0) {
            if ( (a == INF || b == INF) || (a != b) ) {
                cout << "YES" << endl;
                return 0;
            }
        }
    }
    cout << "NO" << endl;

}