public static void main ( String [ ] args ) {
  Scanner in = new Scanner ( System . in ) ;
  int n = in . nextInt ( ) ;
  int x = in . nextInt ( ) ;
  int a0 = in . nextInt ( ) ;
  int b0 = in . nextInt ( ) ;
  int lastElement = 0 ;
  for ( int i = 1 ;
  i <= 6 ;
  i ++ ) {
    if ( i == a0 || i == 7 - a0 ) continue ;
    if ( i == b0 || i == 7 - b0 ) continue ;
    if ( i == x ) continue ;
    lastElement = i ;
  }
  for ( int i = 0 ;
  i < n - 1 ;
  i ++ ) {
    int a = in . nextInt ( ) ;
    int b = in . nextInt ( ) ;
    int firstNumber = getFirstNumber ( a , b ) ;
    int secondNumber = getSecondNumber ( a , b , firstNumber ) ;
    if ( firstNumber != lastElement && secondNumber != lastElement ) {
      System . out . println ( "NO" ) ;
      return ;
    }
  }
  System . out . println ( "YES" ) ;
}

public static void main ( String [ ] args ) { Scanner in = new Scanner ( System . in ) ; int n = in . nextInt ( ) ; int x = in . nextInt ( ) ; int a0 = in . nextInt ( ) ; int b0 = in . nextInt ( ) ; int lastElement = 0 ; for ( int i = 1 ; i <= 6 ; i ++ ) { if ( i == a0 || i == 7 - a0 ) continue ; if ( i == b0 || i == 7 - b0 ) continue ; if ( i == x ) continue ; lastElement = i ; } for ( int i = 0 ; i < n - 1 ; i ++ ) { int a = in . nextInt ( ) ; int b = in . nextInt ( ) ; int firstNumber = getFirstNumber ( a , b ) ; int secondNumber = getSecondNumber ( a , b , firstNumber ) ; if ( firstNumber != lastElement && secondNumber != lastElement ) { System . out . println ( " NO " ) ; return ; } } System . out . println ( " YES " ) ; }
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