#include <iostream>
#include <fstream>
#include <vector>
#include <cstring>
#include <string>
#include <algorithm>
#include <iomanip>
using namespace std;
template<typename T> void setmin(T& a, T& b) { a = min(a, b); }
template<typename T> void setmax(T& a, T& b) { a = max(a, b); }

typedef pair<int, int> P;

int N, M;

vector<int> G[20001];
int group[20001];

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	cin >> N >> M;
	for(int i = 0; i < M; i++) {
		int a, b;
		cin >> a >> b;
		G[a].push_back(b);
		G[b].push_back(a);
	}
	group[1] = 0;
	int g = 1;
	vector<P> one;
	for(int c : G[1]) {
		one.push_back(P(c, g));
		group[c] = g;
		g++;
	}

	vector<P> two;
	for(P p : one) {
		for(int c : G[p.first]) {
			if(c == 1 || group[c] != 0) continue;
			group[c] = p.second;
			two.push_back(P(c, p.second));
		}
	}

	for(P p : two) {
		for(int c : G[p.first]) {
			if(group[c] != 0 && group[c] != p.second) {
				cout << "YES" << endl;
				return 0;
			}
		}
	}
	cout << "NO" << endl;
}