#include <bits/stdc++.h>

using namespace std;

// 1 b c d e 1
int N, M, u, v;
bool check[20005];
vector <pair<int, int>> E;
vector <int> adj[20005];

int main(void)
{
	cin.tie(0);
	ios::sync_with_stdio(false);
	
	cin >> N >> M;

	for (int i = 0; i < M; i++)
	{
		cin >> u >> v;
		E.push_back(make_pair(u, v));
		if (u == 1)
		{
			check[v] = true;
		}
		if (v == 1)
		{
			check[u] = true;
		}
	}

	for (int i = 0; i < M; i++)
	{
		u = E[i].first;
		v = E[i].second;
		if (check[u] && v!=1)
		{
			adj[v].push_back(u);
		}
		if (check[v] && u!=1)
		{
			adj[u].push_back(v);
		}
	}
	
	for (int i = 0; i < M; i++)
	{
		bitset <20005> check1, check2, temp;
		u = E[i].first;
		v = E[i].second;
		if (u == 1 || v == 1) continue;
		for (auto k : adj[u])
		{
			if (k == u || k == v) continue;
			check1[k] = true;
		}
		for (auto k : adj[v])
		{
			if (k == u || k == v) continue;
			check2[k] = true;
		}
		temp = (check1 | check2);
		if (temp.count() >= 2)
		{
			cout << "YES" << '\n';
			return 0;
		}
	}
	cout << "NO" << '\n';
	return 0;
}