#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
//-------------------------------------------------------

int N,M;
vector<int> E[202020];
int yes[202020];
vector<int> S;
bitset<202020> B;

void dfs(int cur,int d) {
	if(d==5) {
		if(yes[cur]) {
			_P("YES\n");
			exit(0);
		}
		return;
	}
	
	int i;
	FORR(e,E[cur]) {
		if(B[e]) continue;
		B[e]=1;
		dfs(e,d+1);
		B[e]=0;
	}
}

void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N>>M;
	FOR(i,M) {
		cin>>x>>y;
		E[x-1].push_back(y-1);
		E[y-1].push_back(x-1);
		if(x==1) yes[y-1]=1;
		if(y==1) yes[x-1]=1;
	}
	
	B.set(0);
	dfs(0,1);
	_P("NO\n");
	
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n';
	FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	solve(); return 0;
}