#define _CRT_SECURE_NO_WARNINGS // #pragma warning(disable:4996)
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <string>
#include <queue>
#include <functional>
#include <sstream>
#include <cmath>
#include <set>
#include <map>
#include <unordered_set>
using namespace std; 

#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define pb push_back
#define mp(a,b) make_pair(a,b)
#define all(a) a.begin(),a.end()
#define len(x) ((int)(x).size())
#define tmax(a,b,c) max((a),max((b),(c)))
#define debug(x) cerr << #x << " is " << x << endl;

typedef pair<int, int> Pii;
typedef vector<int> V;
typedef vector<vector<int> > VV;
typedef long long ll;
const int inf = 2e9;
const int mod = 1e9 + 7;
const long double eps = 1e-10;

int N, M;
V E1[20001];
unordered_set<int> E2[20001];

int main()
{
	cin >> N >> M;
	rep(i,0,M) {
		int a, b; cin >> a >> b;
		a--; b--;
		E1[a].pb(b);
		E1[b].pb(a);
	}

	for (int b: E1[0]) {
		for (int c: E1[b]) {
			if (c==0) continue;
			E2[c].insert(b);
			//printf("b=%d c=%d\n",b,c);
		}
	}

	rep(i,0,M-1) {
		if (!E2[i].size()) continue;
		rep(j,i+1,M) {
			if (!E2[j].size()) continue;
			//printf("i=%d j=%d\n",i,j);
			auto it = find(all(E1[i]), j);
			if (it != E1[i].end()) {
				if (E2[i].size() == 1 && E2[j].size() == 1 && E2[i] != E2[j]
				||  E2[i].size()>=1 && E2[j].size()>=1 && max(E2[i].size(), E2[j].size())>=2) {
					cout << "YES" << endl;
					return 0;
				}
			} 
		}
	}

	cout << "NO" << endl;
	return 0;
}