public static void main ( String [ ] args ) {
  int n = scanner . nextInt ( ) , k = scanner . nextInt ( ) ;
  int [ ] h = IntStream . range ( 0 , n ) . map ( i -> scanner . nextInt ( ) ) . sorted ( ) . toArray ( ) ;
  System . out . println ( IntStream . range ( k - 1 , n ) . map ( i -> h [ i ] - h [ i - k + 1 ] ) . min ( ) . getAsInt ( ) ) ;
}

public static void main ( String [ ] args ) { int n = scanner . nextInt ( ) , k = scanner . nextInt ( ) ; int [ ] h = IntStream . range ( 0 , n ) . map ( i -> scanner . nextInt ( ) ) . sorted ( ) . toArray ( ) ; System . out . println ( IntStream . range ( k - 1 , n ) . map ( i -> h [ i ] - h [ i - k + 1 ] ) . min ( ) . getAsInt ( ) ) ; }
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