public static void main ( String [ ] args ) {
  Scanner scan = new Scanner ( System . in ) ;
  int N = scan . nextInt ( ) ;
  int [ ] a = IntStream . range ( 0 , N ) . map ( i -> scan . nextInt ( ) ) . toArray ( ) ;
  Map < Integer , Integer > map = new HashMap < > ( ) ;
  for ( int i = 0 ;
  i < N ;
  ++ i ) {
    if ( ! map . containsKey ( a [ i ] ) ) {
      map . put ( a [ i ] , 0 ) ;
    }
    map . put ( a [ i ] , map . get ( a [ i ] ) + 1 ) ;
  }
  int ans = 0 ;
  for ( Map . Entry < Integer , Integer > entry : map . entrySet ( ) ) {
    if ( entry . getKey ( ) > entry . getValue ( ) ) {
      ans += entry . getValue ( ) ;
    }
    else {
      ans += entry . getValue ( ) - entry . getKey ( ) ;
    }
  }
  System . out . println ( ans ) ;
}

public static void main ( String [ ] args ) { Scanner scan = new Scanner ( System . in ) ; int N = scan . nextInt ( ) ; int [ ] a = IntStream . range ( 0 , N ) . map ( i -> scan . nextInt ( ) ) . toArray ( ) ; Map < Integer , Integer > map = new HashMap < > ( ) ; for ( int i = 0 ; i < N ; ++ i ) { if ( ! map . containsKey ( a [ i ] ) ) { map . put ( a [ i ] , 0 ) ; } map . put ( a [ i ] , map . get ( a [ i ] ) + 1 ) ; } int ans = 0 ; for ( Map . Entry < Integer , Integer > entry : map . entrySet ( ) ) { if ( entry . getKey ( ) > entry . getValue ( ) ) { ans += entry . getValue ( ) ; } else { ans += entry . getValue ( ) - entry . getKey ( ) ; } } System . out . println ( ans ) ; }
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