public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int N = sc . nextInt ( ) ;
  int a [ ] = new int [ N ] ;
  for ( int i = 0 ;
  i < N ;
  i ++ ) {
    a [ i ] = sc . nextInt ( ) ;
  }
  TreeSet < Integer > set = new TreeSet < > ( ) ;
  int s = 0 ;
  int ans = 1 ;
  set . add ( a [ 0 ] ) ;
  for ( int t = 1 ;
  t < N ;
  t ++ ) {
    if ( set . contains ( a [ t ] ) ) {
      while ( set . contains ( a [ t ] ) ) {
        set . remove ( a [ s ] ) ;
        s ++ ;
      }
      set . add ( a [ t ] ) ;
      ans = Math . max ( ans , t - s + 1 ) ;
    }
    else {
      set . add ( a [ t ] ) ;
      ans = Math . max ( ans , t - s + 1 ) ;
    }
  }
  System . out . println ( ans ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int N = sc . nextInt ( ) ; int a [ ] = new int [ N ] ; for ( int i = 0 ; i < N ; i ++ ) { a [ i ] = sc . nextInt ( ) ; } TreeSet < Integer > set = new TreeSet < > ( ) ; int s = 0 ; int ans = 1 ; set . add ( a [ 0 ] ) ; for ( int t = 1 ; t < N ; t ++ ) { if ( set . contains ( a [ t ] ) ) { while ( set . contains ( a [ t ] ) ) { set . remove ( a [ s ] ) ; s ++ ; } set . add ( a [ t ] ) ; ans = Math . max ( ans , t - s + 1 ) ; } else { set . add ( a [ t ] ) ; ans = Math . max ( ans , t - s + 1 ) ; } } System . out . println ( ans ) ; }
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