public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  long k = sc . nextLong ( ) ;
  int [ ] p = new int [ 44 ] ;
  long [ ] a1 = new long [ n ] ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    long a = sc . nextLong ( ) ;
    a1 [ i ] = a ;
    int count = 0 ;
    while ( a > 0 ) {
      if ( ( a & 1 ) == 1 ) {
        p [ count ] ++ ;
      }
      a >>= 1 ;
      count ++ ;
    }
  }
  long [ ] pow = new long [ 44 ] ;
  pow [ 0 ] = 1 ;
  for ( int i = 1 ;
  i < 44 ;
  i ++ ) {
    pow [ i ] = pow [ i - 1 ] * 2 ;
  }
  long ans = 0 ;
  for ( int i = 43 ;
  i >= 0 ;
  i -- ) {
    if ( p [ i ] * 2 <= n ) {
      if ( ans + pow [ i ] <= k ) {
        ans += pow [ i ] ;
      }
    }
  }
  long an = 0 ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    an += ans ^ a1 [ i ] ;
  }
  System . out . println ( an ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; long k = sc . nextLong ( ) ; int [ ] p = new int [ 44 ] ; long [ ] a1 = new long [ n ] ; for ( int i = 0 ; i < n ; i ++ ) { long a = sc . nextLong ( ) ; a1 [ i ] = a ; int count = 0 ; while ( a > 0 ) { if ( ( a & 1 ) == 1 ) { p [ count ] ++ ; } a >>= 1 ; count ++ ; } } long [ ] pow = new long [ 44 ] ; pow [ 0 ] = 1 ; for ( int i = 1 ; i < 44 ; i ++ ) { pow [ i ] = pow [ i - 1 ] * 2 ; } long ans = 0 ; for ( int i = 43 ; i >= 0 ; i -- ) { if ( p [ i ] * 2 <= n ) { if ( ans + pow [ i ] <= k ) { ans += pow [ i ] ; } } } long an = 0 ; for ( int i = 0 ; i < n ; i ++ ) { an += ans ^ a1 [ i ] ; } System . out . println ( an ) ; }
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