public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  while ( sc . hasNextInt ( ) ) {
    int N = sc . nextInt ( ) ;
    Map < Integer , Integer > cnt = new HashMap < > ( ) ;
    for ( int i = 0 ;
    i < N ;
    i ++ ) {
      int x = sc . nextInt ( ) ;
      int c = 1 ;
      if ( cnt . containsKey ( x ) ) {
        c = cnt . get ( x ) + 1 ;
      }
      cnt . put ( x , c ) ;
    }
    int ans = 0 ;
    for ( int x : cnt . keySet ( ) ) {
      int c = cnt . get ( x ) ;
      if ( c < x ) {
        ans += c ;
      }
      else if ( c > x ) {
        ans += c - x ;
      }
    }
    System . out . println ( ans ) ;
  }
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; while ( sc . hasNextInt ( ) ) { int N = sc . nextInt ( ) ; Map < Integer , Integer > cnt = new HashMap < > ( ) ; for ( int i = 0 ; i < N ; i ++ ) { int x = sc . nextInt ( ) ; int c = 1 ; if ( cnt . containsKey ( x ) ) { c = cnt . get ( x ) + 1 ; } cnt . put ( x , c ) ; } int ans = 0 ; for ( int x : cnt . keySet ( ) ) { int c = cnt . get ( x ) ; if ( c < x ) { ans += c ; } else if ( c > x ) { ans += c - x ; } } System . out . println ( ans ) ; } }
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