public static void main ( String [ ] args ) throws IOException {
  FastReader sc = new FastReader ( ) ;
  PrintWriter out = new PrintWriter ( System . out ) ;
  int t = sc . nextInt ( ) ;
  int lowerface = 7 - sc . nextInt ( ) ;
  sc . nextLine ( ) ;
  boolean found = true ;
  while ( t -- > 1 ) {
    found = false ;
    int [ ] faceval = new int [ 7 ] ;
    int a = sc . nextInt ( ) ;
    int b = sc . nextInt ( ) ;
    faceval [ a ] ++ ;
    faceval [ 7 - a ] ++ ;
    faceval [ b ] ++ ;
    faceval [ 7 - b ] ++ ;
    for ( int i = 1 ;
    i < 7 ;
    i ++ ) {
      if ( faceval [ i ] < 1 && lowerface == i ) {
        found = true ;
        break ;
      }
    }
    if ( ! found ) break ;
  }
  out . println ( found ? "YES" : "NO" ) ;
  out . close ( ) ;
}

public static void main ( String [ ] args ) throws IOException { FastReader sc = new FastReader ( ) ; PrintWriter out = new PrintWriter ( System . out ) ; int t = sc . nextInt ( ) ; int lowerface = 7 - sc . nextInt ( ) ; sc . nextLine ( ) ; boolean found = true ; while ( t -- > 1 ) { found = false ; int [ ] faceval = new int [ 7 ] ; int a = sc . nextInt ( ) ; int b = sc . nextInt ( ) ; faceval [ a ] ++ ; faceval [ 7 - a ] ++ ; faceval [ b ] ++ ; faceval [ 7 - b ] ++ ; for ( int i = 1 ; i < 7 ; i ++ ) { if ( faceval [ i ] < 1 && lowerface == i ) { found = true ; break ; } } if ( ! found ) break ; } out . println ( found ? " YES " : " NO " ) ; out . close ( ) ; }
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