public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  int t = sc . nextInt ( ) ;
  Point [ ] p = new Point [ n ] ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    long x = sc . nextLong ( ) ;
    long y = sc . nextLong ( ) ;
    p [ i ] = new Point ( x , y ) ;
  }
  long ans = Long . MAX_VALUE ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    for ( int j = 0 ;
    j < n ;
    j ++ ) {
      for ( int k = 0 ;
      k < n ;
      k ++ ) {
        for ( int l = 0 ;
        l < n ;
        l ++ ) {
          int count = 0 ;
          for ( int u = 0 ;
          u < n ;
          u ++ ) {
            if ( p [ u ] . x <= p [ i ] . x && p [ u ] . x >= p [ j ] . x && p [ u ] . y <= p [ k ] . y && p [ u ] . y >= p [ l ] . y ) {
              count ++ ;
            }
          }
          if ( count >= t ) {
            ans = Math . min ( ans , ( p [ i ] . x - p [ j ] . x ) * ( p [ k ] . y - p [ l ] . y ) ) ;
          }
        }
      }
    }
  }
  System . out . println ( ans ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; int t = sc . nextInt ( ) ; Point [ ] p = new Point [ n ] ; for ( int i = 0 ; i < n ; i ++ ) { long x = sc . nextLong ( ) ; long y = sc . nextLong ( ) ; p [ i ] = new Point ( x , y ) ; } long ans = Long . MAX_VALUE ; for ( int i = 0 ; i < n ; i ++ ) { for ( int j = 0 ; j < n ; j ++ ) { for ( int k = 0 ; k < n ; k ++ ) { for ( int l = 0 ; l < n ; l ++ ) { int count = 0 ; for ( int u = 0 ; u < n ; u ++ ) { if ( p [ u ] . x <= p [ i ] . x && p [ u ] . x >= p [ j ] . x && p [ u ] . y <= p [ k ] . y && p [ u ] . y >= p [ l ] . y ) { count ++ ; } } if ( count >= t ) { ans = Math . min ( ans , ( p [ i ] . x - p [ j ] . x ) * ( p [ k ] . y - p [ l ] . y ) ) ; } } } } } System . out . println ( ans ) ; }
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