#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;

int main()
{
	int n, m;
	cin>>n>>m;
	int a[50000], b[50000];
	vector<int> g[20000];
	for(int i=0; i<m; i++){
		cin>>a[i]>>b[i];
		a[i]--; b[i]--;
		g[a[i]].push_back(b[i]);
		g[b[i]].push_back(a[i]);
	}
	bitset<20000> bs[20000];
	for(auto p:g[0]){
		for(auto y:g[p]){
			if(y==0) continue;
			bs[y][p]=1;
		}
	}
	for(int i=0; i<m; i++){
		if(a[i]==0 || b[i]==0) continue;
		bool nuo1=0, nuo2=0;
		if(bs[a[i]][b[i]]) nuo1=1, bs[a[i]][b[i]]=0;
		if(bs[b[i]][a[i]]) nuo2=1, bs[b[i]][a[i]]=0;
		int c1=bs[a[i]].count(), c2=bs[b[i]].count();
		if(c1==0 || c2==0){
			if(nuo1) bs[a[i]][b[i]]=1;
			if(nuo2) bs[b[i]][a[i]]=1;
			continue;
		}
		if(c1>=2 || c2>=2){
			cout<<"YES"<<endl;
			return 0;
		}
		if((bs[a[i]]&bs[b[i]]).count()==0){
			cout<<"YES"<<endl;
			return 0;
		}
		if(nuo1) bs[a[i]][b[i]]=1;
		if(nuo2) bs[b[i]][a[i]]=1;
	}
	cout<<"NO"<<endl;
    return 0;
}