#include <iostream>
#include <vector>
#include <set>
#define repeat(i,n) for (int i = 0; (i) < (n); ++(i))
using namespace std;
int main() {
    // input
    int n, m; cin >> n >> m;
    vector<int> a(m), b(m);
    repeat (i,m) {
        cin >> a[i] >> b[i];
        -- a[i]; -- b[i];
    }
    // select vertices and edges
    const int root = 0;
    set<int> v1;
    repeat (i,m) {
        if (b[i] == root) v1.insert(a[i]);
        if (a[i] == root) v1.insert(b[i]);
    }
    vector<set<int> > g1(n);
    repeat (i,m) {
        if (v1.count(b[i])) g1[a[i]].insert(b[i]);
        if (v1.count(a[i])) g1[b[i]].insert(a[i]);
    }
    // find a cycle
    bool ans = false;
    repeat (e,m) {
        int i = a[e];
        int j = b[e];
        if (i == root or j == root) continue;
        bool g1_i_count_j = g1[i].count(j); g1[i].erase(j);
        bool g1_j_count_i = g1[j].count(i); g1[j].erase(i);
        if (not g1[i].empty() and not g1[j].empty()) {
            if (g1[i].size() >= 2 or g1[j].size() >= 2 or g1[i] != g1[j]) {
                ans = true;
            }
        }
        if (g1_i_count_j) g1[i].insert(j);
        if (g1_j_count_i) g1[j].insert(i);
        if (ans) break;
    }
    // output
    cout << (ans ? "YES" : "NO") << endl;
    return 0;
}