public static void main ( String [ ] args ) {
  FastScanner fs = new FastScanner ( ) ;
  int T = 1 ;
  PrintWriter out = new PrintWriter ( System . out ) ;
  for ( int tt = 0 ;
  tt < T ;
  tt ++ ) {
    int n = fs . nextInt ( ) ;
    int arr [ ] = fs . readArray ( n ) ;
    int count [ ] = new int [ 1001 ] ;
    ArrayList < Integer > ans = new ArrayList < > ( ) ;
    for ( int i = n - 1 ;
    i >= 0 ;
    i -- ) {
      count [ arr [ i ] ] ++ ;
      if ( count [ arr [ i ] ] == 1 ) ans . add ( arr [ i ] ) ;
    }
    System . out . println ( ans . size ( ) ) ;
    Collections . reverse ( ans ) ;
    for ( int i : ans ) {
      System . out . print ( i + " " ) ;
    }
    System . out . println ( ) ;
  }
  out . close ( ) ;
}

public static void main ( String [ ] args ) { FastScanner fs = new FastScanner ( ) ; int T = 1 ; PrintWriter out = new PrintWriter ( System . out ) ; for ( int tt = 0 ; tt < T ; tt ++ ) { int n = fs . nextInt ( ) ; int arr [ ] = fs . readArray ( n ) ; int count [ ] = new int [ 1001 ] ; ArrayList < Integer > ans = new ArrayList < > ( ) ; for ( int i = n - 1 ; i >= 0 ; i -- ) { count [ arr [ i ] ] ++ ; if ( count [ arr [ i ] ] == 1 ) ans . add ( arr [ i ] ) ; } System . out . println ( ans . size ( ) ) ; Collections . reverse ( ans ) ; for ( int i : ans ) { System . out . print ( i + " ▁ " ) ; } System . out . println ( ) ; } out . close ( ) ; }
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