#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;

int main() {
	int N, M;
	cin >> N >> M;
	 vector<int> graph[20010];
	for (int i = 0; i < M; i++)
	{
		int a, b;
		cin >> a >> b;
		graph[a].push_back(b);
		graph[b].push_back(a);

	}
	vector<pair<int, int> > p;
	for (int i = 0; i < graph[1].size(); i++)
	{
		int a = graph[1][i];
		for (int j = 0; j < graph[a].size(); j++)
		{
			int b = graph[a][j];
			if (b == 1)
				continue;
			p.push_back(make_pair(a, b));
		}
	}
	for (int i = 0; i+1 < p.size(); i++)
	{
		int a1 = p[i].first, b1 = p[i].second, a2 = p[i + 1].first, b2 = p[i + 1].second;
		if (a1 == a2 || b1 == b2)
			continue;
			auto it = find(graph[b1].begin(), graph[b1].end(), b2);
			if (it != graph[b1].end()); {
				//cout << a1 << " " << b1 << " " << a2 << " " << b2 << endl;
				cout << "YES" << endl;
				return 0;
			}
		
	}
	cout << "NO" << endl;
	return 0;
}