public static void main ( String [ ] args ) {
  Scanner scan = new Scanner ( System . in ) ;
  int N = scan . nextInt ( ) ;
  int [ ] [ ] box = new int [ N ] [ 2 ] ;
  for ( int i = 0 ;
  i < N ;
  i ++ ) {
    box [ i ] [ 0 ] = scan . nextInt ( ) ;
    box [ i ] [ 1 ] = scan . nextInt ( ) ;
  }
  Arrays . sort ( box , new ArraySort ( ) ) ;
  final int INF = 1000000000 ;
  int dp [ ] = new int [ N + 1 ] ;
  int dpw [ ] = new int [ N + 1 ] ;
  for ( int i = 0 ;
  i < N + 1 ;
  i ++ ) {
    dp [ i ] = INF ;
    dpw [ i ] = INF ;
  }
  for ( int i = 0 ;
  i < N ;
  i ++ ) {
    int result = Arrays . binarySearch ( dp , box [ i ] [ 1 ] ) ;
    int insertionPoint = ( result >= 0 ) ? result : ~ result ;
    dp [ insertionPoint ] = box [ i ] [ 1 ] ;
    dpw [ insertionPoint ] = box [ i ] [ 0 ] ;
  }
  for ( int i = 0 ;
  i < N ;
  i ++ ) {
    if ( dp [ i + 1 ] == INF ) {
      System . out . println ( i + 1 ) ;
      break ;
    }
  }
}

public static void main ( String [ ] args ) { Scanner scan = new Scanner ( System . in ) ; int N = scan . nextInt ( ) ; int [ ] [ ] box = new int [ N ] [ 2 ] ; for ( int i = 0 ; i < N ; i ++ ) { box [ i ] [ 0 ] = scan . nextInt ( ) ; box [ i ] [ 1 ] = scan . nextInt ( ) ; } Arrays . sort ( box , new ArraySort ( ) ) ; final int INF = 1000000000 ; int dp [ ] = new int [ N + 1 ] ; int dpw [ ] = new int [ N + 1 ] ; for ( int i = 0 ; i < N + 1 ; i ++ ) { dp [ i ] = INF ; dpw [ i ] = INF ; } for ( int i = 0 ; i < N ; i ++ ) { int result = Arrays . binarySearch ( dp , box [ i ] [ 1 ] ) ; int insertionPoint = ( result >= 0 ) ? result : ~ result ; dp [ insertionPoint ] = box [ i ] [ 1 ] ; dpw [ insertionPoint ] = box [ i ] [ 0 ] ; } for ( int i = 0 ; i < N ; i ++ ) { if ( dp [ i + 1 ] == INF ) { System . out . println ( i + 1 ) ; break ; } } }
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