#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef vector< int > vi;
typedef vector< vi > vvi;
typedef vector< ll > vl;
typedef vector< vl > vvl;
typedef pair< int, int > pii;
typedef vector< pii > vp;
typedef vector< double > vd;
typedef vector< vd > vvd;
typedef vector< string > vs;

template< class T1, class T2 >
int upmin( T1 &x, T2 v ){
  if( x > v ){
    x = v;
    return 1;
  }
  return 0;
}

template< class T1, class T2 >
int upmax( T1 &x, T2 v ){
  if( x < v ){
    x = v;
    return 1;
  }
  return 0;
}

const int INF = 0x3f3f3f3f;

int N, M;
vi A, B;

void init(){
  cin >> N >> M;
  A = B = vi( M );
  for( int i = 0; i < M; ++i )
    cin >> A[ i ] >> B[ i ];
}

vvi G;

void preprocess(){
  G = vvi( N );
  for( int i = 0; i < M; ++i )
    G[ A[ i ] - 1 ].emplace_back( B[ i ] - 1 ),
    G[ B[ i ] - 1 ].emplace_back( A[ i ] - 1 );
}

void solve(){
  vi col( N );
  for( int t = 0; t < 200; ++t ){
    for( int i = 1; i < N; ++i )
      col[ i ] = rand() % 4;
    vvi dp( 1 << 4, vi( N ) );
    queue< tuple< int, int > > que;
    for( int u : G[ 0 ] )
      dp[ 1 << col[ u ] ][ u ] = 1,
      que.emplace( 1 << col[ u ], u );
    while( not que.empty() ){
      int s, u; tie( s, u ) = que.front(); que.pop();
      for( int v : G[ u ] ) if( v != 0 )
        if( ~s & 1 << col[ v ] )
          if( upmax( dp[ s | 1 << col[ v ] ][ v ], 1 ) )
            que.emplace( s | 1 << col[ v ], v );
    }
    for( int u : G[ 0 ] )
      if( dp[ ( 1 << 4 ) - 1 ][ u ] )
        cout << "YES" << endl, exit( 0 );
  }
  cout << "NO" << endl;
}

signed main(){
  ios::sync_with_stdio( 0 );
  init();
  preprocess();
  solve();
  return 0;
}