#include <cstdio>
#include <cstring>
#include <string>
#include <cmath>
#include <cassert>
#include <iostream>
#include <algorithm>
#include <stack>
#include <queue>
#include <vector>
#include <set>
#include <map>
#include <bitset>
using namespace std;

#define repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repl(i,0,n)
#define mp(a,b) make_pair(a,b)
#define pb(a) push_back(a)
#define all(x) (x).begin(),(x).end()
#define dbg(x) cout<<#x"="<<x<<endl
#define fi first
#define se second

#define INF 2147483600

#define N 20000
#define M 50000
#define MK (1<<4)
vector<int> graph[N];
int color[N];
bool dp[MK][N];

void dfs(int p, int mask){
  if(dp[mask][p]) return;
  dp[mask][p] = true;
  for(auto to : graph[p]){
    if((mask&color[to])==0) dfs(to, mask|color[to]);
  }
}

int main(){
  int n,m;
  cin>>n>>m;
  rep(i,m){
    int a,b;
    scanf("%d %d", &a, &b);
    a--;b--;
    graph[a].pb(b);
    graph[b].pb(a);
  }

  color[0]=0;
  rep(reps, 500){
    repl(i,1,n) color[i] = 1<<(rand()%4);
    fill(dp[0], dp[MK], false);
    dfs(0,0);
    for(auto t : graph[0]) if(dp[MK-1][t]){
      cout<<"YES"<<endl;
      return 0;
    }
  }

  cout<<"NO"<<endl;

  return 0;
}