#include <bits/stdc++.h> using namespace std; const int N = (int) 5e4; vector<int> graph[N]; vector<int> nice[N]; bool visited[N]; int depth[N], a[N], b[N]; int main() { ios::sync_with_stdio(false); int n; cin >> n; int m; cin >> m; for (int i = 0; i < m; ++i) { int u, v; cin >> u >> v; --u; --v; graph[u].push_back(v); graph[v].push_back(u); a[i] = u; b[i] = v; } queue<int> q; visited[0] = true; q.push(0); while (!q.empty()) { int u = q.front(); q.pop(); for (auto v : graph[u]) if (!visited[v]) { visited[v] = true; depth[v] = depth[u] + 1; q.push(v); } } for (int i = 0; i < m; ++i) { if (depth[a[i]] == 1) nice[b[i]].push_back(a[i]); if (depth[b[i]] == 1) nice[a[i]].push_back(b[i]); } for (int i = 0; i < m; ++i) if (a[i] != 0 && b[i] != 0) { if (nice[a[i]].size() > 2 && nice[b[i]].size() > 2) { cout << "YES" << endl; return 0; } for (auto x : nice[a[i]]) if (x != b[i]) for (auto y : nice[b[i]]) if (y != a[i] && x != y) { cout << "YES" << endl; return 0; } } cout << "NO" << endl; return 0; }