#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 tmin(a,b,c) min((a),min((b),(c)))
#define debug(x) cerr << #x << " is " << x << endl;

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

int N, M;
Vi A[50001];
Vi B[50001];

int main()
{
	cin >> N >> M;
	rep(i,0,M) {
		int a, b;
		scanf("%d %d", &a, &b);
		a--; b--;
		A[a].pb(b);
		A[b].pb(a);
	}

	for (auto a: A[0]) {
		for (auto b: A[a]) {
			if (b) B[b].pb(a);
		}
	}

	rep(i, 0, N - 1) {
		if (B[i].size()) {
			rep(j, i+1, N) {
				if (B[j].size()) {
					//printf("i=%d, j=%d\n",i,j);
					auto it = find(all(A[j]), i);
					if (it != A[j].end()) {
						if (B[i].size() == 1 && B[j].size() == 1) {
							if (B[i][0] != B[j][0]) {
								cout << "YES" << endl;
								return 0;
							} 
						}
						else if (B[i].size() >= 1 && B[j].size() >= 1 && max(B[i].size(), B[j].size()) >= 2) {
							cout << "YES" << endl;
							return 0;
						}
					}
				}
			}
		}
	}
	cout << "NO" << endl;
	return 0;
}