public static void main ( String [ ] args ) {
  Scanner input = new Scanner ( System . in ) ;
  int n = input . nextInt ( ) ;
  TreeSet < Integer > remainNumber = new TreeSet < > ( ) ;
  TreeSet < Integer > checkingNumber = new TreeSet < > ( ) ;
  StringBuilder ans = new StringBuilder ( ) ;
  for ( int i = 1 ;
  i <= n ;
  i ++ ) remainNumber . add ( i ) ;
  int a [ ] = new int [ n ] ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    a [ i ] = input . nextInt ( ) ;
    remainNumber . remove ( a [ i ] ) ;
  }
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    int len = checkingNumber . size ( ) ;
    if ( a [ i ] <= n ) checkingNumber . add ( a [ i ] ) ;
    if ( len == checkingNumber . size ( ) ) {
      ans . append ( remainNumber . pollFirst ( ) + " " ) ;
    }
    else {
      ans . append ( a [ i ] + " " ) ;
    }
  }
  System . out . println ( ans ) ;
}

public static void main ( String [ ] args ) { Scanner input = new Scanner ( System . in ) ; int n = input . nextInt ( ) ; TreeSet < Integer > remainNumber = new TreeSet < > ( ) ; TreeSet < Integer > checkingNumber = new TreeSet < > ( ) ; StringBuilder ans = new StringBuilder ( ) ; for ( int i = 1 ; i <= n ; i ++ ) remainNumber . add ( i ) ; int a [ ] = new int [ n ] ; for ( int i = 0 ; i < n ; i ++ ) { a [ i ] = input . nextInt ( ) ; remainNumber . remove ( a [ i ] ) ; } for ( int i = 0 ; i < n ; i ++ ) { int len = checkingNumber . size ( ) ; if ( a [ i ] <= n ) checkingNumber . add ( a [ i ] ) ; if ( len == checkingNumber . size ( ) ) { ans . append ( remainNumber . pollFirst ( ) + " ▁ " ) ; } else { ans . append ( a [ i ] + " ▁ " ) ; } } System . out . println ( ans ) ; }
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