#include <bits/stdc++.h>
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define FORR(i,a,b) for (int i=(a);i>=(b);i--)
#define pb push_back
#define pcnt __builtin_popcount
#define show(x) cout<<#x<<" = "<<x<<endl;
#define maxs(x,y) x = max(x,y)
#define mins(x,y) x = min(x,y)
#define fi first
#define se second
#define rng(a) a.begin(),a.end()
#define each(it,c) for(__typeof((c).begin()) it=(c).begin();it!=(c).end();it++)
#define sz(x) (int)(x).size()
#define mp make_pair

using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vpii;
typedef set<int> si;
typedef pair<ll,ll> pll;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<pll> vpll;
typedef set<ll> sl;
template<typename T>string join(vector<T>&v)
{stringstream s;FOR(i,0,sz(v))s<<' '<<v[i];return s.str().substr(1);}
ll gcd(ll a,ll b){if(a>b)swap(a,b);for(;a>0;b%=a,swap(a,b));return b;}
int modpow(ll a,ll n,int m){if(a==0)return a;ll p=1;for(;n>0;n/=2,a=a*a%m)if(n&1)p=p*a%m;return(int)p;}
void dout(double d){printf("%.12f\n",d);}

const int iinf = 1e9;
const ll linf = 1e18;
const int mod = 1e9+7;
const double pi = acos(-1);
const double eps = 1e-10;
const int N = 200005;

int n, m;
vi E[N], E2[N];
bool check(int a, int b){
  int la = sz(E2[a]), lb = sz(E2[b]);
  if(la > 1 && lb > 2 || la > 2 && lb > 1)return true;
  int ca = 0, cb = 0, va, vb;
  each(itr, E2[a]) if(*itr != b){
    ca++;
    va = *itr;
  }
  each(itr, E2[b]) if(*itr != a){
    cb++;
    vb = *itr;
  }
  if(ca == 0 || cb == 0)return false;
  if(ca + cb > 2)return true;
  return va != vb;
}
main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  cin >> n >> m;
  FOR(i, 0, m){
    int a, b;
    cin >> a >> b;
    if(a > b) swap(a, b);
    E[a].pb(b);
    if(a > 1)E[b].pb(a);
  }
  each(itr, E[1])each(itr2, E[*itr]) E2[*itr2].pb(*itr);
  FOR(i, 2, n){
    each(itr, E[i]){
      int j = *itr;
      if(j < i)continue;
      if(check(i, j)){
        cout << "YES\n";
        return 0;
      }
    }
  }
  cout << "NO\n";
  return 0;
}