fn.cpp

#include <algorithm>
#include <cctype>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
 
using namespace std;
 
#define DEBUG(x) cout << ">>> " << #x << " : " << x << endl;
#define REP(i,a) for (int i = 0; i < (a); ++i)
#define FOR(i,a,b) for (int i = (a); i <= (b); ++i)
#define FORD(i,a,b) for (int i = (a); i >= (b); --i)
inline bool EQ(double a, double b) { return fabs(a-b) < 1e-9; }
const int INF = 1<<29;
 
typedef long long ll;
 
#define maxN 10005
 
int n,m;
int x,y;
vector<int> edges[maxN];
bool found,found2;
bool visited[maxN];
 
void comp(int u){
	if(visited[u]) return;
	visited[u]=true;
	if(edges[u].size()>=4) found2=true;
	if(edges[u].size()==3 && found) found2=true;
	if(edges[u].size()==3) found=true;
	REP(i,edges[u].size()){
		comp(edges[u][i]);
	}
}
 
int main() {
	while(scanf("%d%d",&n,&m)==2){
		REP(i,n) edges[i].clear();
		REP(i,n) visited[i]=false;
		found=found2=false;
		REP(i,m){
			scanf("%d%d",&x,&y);
			x--; y--;
			edges[x].push_back(y);
			edges[y].push_back(x);
		}
		REP(i,n){
			found=false;
			comp(i);
		}
		if(found2) printf("YES\n");
		else printf("NO\n");
 
	}
 
	return 0;
}