#include<bits/stdc++.h>
using namespace std;
int n,m;
vector<int>g[100005];
unordered_set<int>s[100005];
int main()
{
	cin>>n>>m;
	for(int i=1,u,v;i<=m;i++)
	{
		cin>>u>>v;
		g[u].push_back(v);
		g[v].push_back(u);
	}
	for(int u:g[1])for(int v:g[u])if(v!=1)s[v].insert(u);
	for(int i=2,a,b,x,y;i<=n;i++)for(int u:g[i])if(u>i)
	{
		a=s[i].size();b=s[u].size();
		if(s[i].count(u))a--;
		if(s[u].count(i))b--;
		if(a==1&&b==1)
		{
			for(int v:s[i])if(v!=i&&v!=u)x=v;
			for(int v:s[u])if(v!=i&&v!=u)y=v;
			if(x!=y){cout<<"YES";return 0;}
		}
		if(a&&b&&(a!=1||b!=1)){cout<<"YES";return 0;}
	}
	cout<<"NO";
}