public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  N = sc . nextInt ( ) ;
  K = sc . nextInt ( ) ;
  trees = new int [ N ] ;
  for ( int i = 0 ;
  i < N ;
  i ++ ) {
    trees [ i ] = sc . nextInt ( ) ;
  }
  sc . close ( ) ;
  Arrays . sort ( trees ) ;
  int current = trees [ K - 1 ] - trees [ 0 ] ;
  int height = 0 ;
  for ( int i = 1 ;
  i < N - K + 1 ;
  i ++ ) {
    height = trees [ i + K - 1 ] - trees [ i ] ;
    if ( current > height ) {
      current = height ;
    }
  }
  System . out . println ( current ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; N = sc . nextInt ( ) ; K = sc . nextInt ( ) ; trees = new int [ N ] ; for ( int i = 0 ; i < N ; i ++ ) { trees [ i ] = sc . nextInt ( ) ; } sc . close ( ) ; Arrays . sort ( trees ) ; int current = trees [ K - 1 ] - trees [ 0 ] ; int height = 0 ; for ( int i = 1 ; i < N - K + 1 ; i ++ ) { height = trees [ i + K - 1 ] - trees [ i ] ; if ( current > height ) { current = height ; } } System . out . println ( current ) ; }
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