public static void main ( String [ ] args ) {
  Scanner scan = new Scanner ( System . in ) ;
  double ax = scan . nextDouble ( ) ;
  double ay = scan . nextDouble ( ) ;
  double dx = scan . nextDouble ( ) - ax ;
  double dy = scan . nextDouble ( ) - ay ;
  int n = scan . nextInt ( ) ;
  double [ ] x = new double [ n ] , y = new double [ n ] ;
  for ( int i = 0 ;
  i < n ;
  ++ i ) {
    double u = scan . nextDouble ( ) - ax ;
    double v = scan . nextDouble ( ) - ay ;
    x [ i ] = ( dx * u + dy * v ) / ( dx * dx + dy * dy ) ;
    y [ i ] = ( - dy * u + dx * v ) / ( dx * dx + dy * dy ) ;
  }
  int k = 0 ;
  for ( int i = 0 ;
  i < n ;
  ++ i ) {
    if ( y [ i ] * y [ ( i + 1 ) % n ] >= 0 ) continue ;
    double z = x [ i ] * y [ ( i + 1 ) % n ] - x [ ( i + 1 ) % n ] * y [ i ] ;
    z /= - y [ i ] + y [ ( i + 1 ) % n ] ;
    if ( z > E && z < 1 - E ) k ++ ;
  }
  System . out . println ( k / 2 + 1 ) ;
}

public static void main ( String [ ] args ) { Scanner scan = new Scanner ( System . in ) ; double ax = scan . nextDouble ( ) ; double ay = scan . nextDouble ( ) ; double dx = scan . nextDouble ( ) - ax ; double dy = scan . nextDouble ( ) - ay ; int n = scan . nextInt ( ) ; double [ ] x = new double [ n ] , y = new double [ n ] ; for ( int i = 0 ; i < n ; ++ i ) { double u = scan . nextDouble ( ) - ax ; double v = scan . nextDouble ( ) - ay ; x [ i ] = ( dx * u + dy * v ) / ( dx * dx + dy * dy ) ; y [ i ] = ( - dy * u + dx * v ) / ( dx * dx + dy * dy ) ; } int k = 0 ; for ( int i = 0 ; i < n ; ++ i ) { if ( y [ i ] * y [ ( i + 1 ) % n ] >= 0 ) continue ; double z = x [ i ] * y [ ( i + 1 ) % n ] - x [ ( i + 1 ) % n ] * y [ i ] ; z /= - y [ i ] + y [ ( i + 1 ) % n ] ; if ( z > E && z < 1 - E ) k ++ ; } System . out . println ( k / 2 + 1 ) ; }
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