public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  HashSet < Integer > set = new HashSet < > ( ) ;
  int [ ] arr = new int [ n ] ;
  int max = 0 ;
  int start = 0 ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    int a = sc . nextInt ( ) ;
    arr [ i ] = a ;
    if ( set . contains ( a ) ) {
      while ( arr [ start ] != a ) {
        set . remove ( arr [ start ] ) ;
        start ++ ;
      }
      start ++ ;
    }
    else {
      set . add ( a ) ;
      int v = set . size ( ) ;
      if ( max < v ) {
        max = v ;
      }
    }
  }
  System . out . println ( max ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; HashSet < Integer > set = new HashSet < > ( ) ; int [ ] arr = new int [ n ] ; int max = 0 ; int start = 0 ; for ( int i = 0 ; i < n ; i ++ ) { int a = sc . nextInt ( ) ; arr [ i ] = a ; if ( set . contains ( a ) ) { while ( arr [ start ] != a ) { set . remove ( arr [ start ] ) ; start ++ ; } start ++ ; } else { set . add ( a ) ; int v = set . size ( ) ; if ( max < v ) { max = v ; } } } System . out . println ( max ) ; }
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