public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  long ax = sc . nextLong ( ) ;
  long ay = sc . nextLong ( ) ;
  long bx = sc . nextLong ( ) ;
  long by = sc . nextLong ( ) ;
  int N = sc . nextInt ( ) ;
  long [ ] x = new long [ N ] ;
  long [ ] y = new long [ N ] ;
  for ( int i = 0 ;
  i < N ;
  i ++ ) {
    x [ i ] = sc . nextLong ( ) ;
    y [ i ] = sc . nextLong ( ) ;
  }
  int count = 0 ;
  for ( int i = 0 ;
  i < N ;
  i ++ ) {
    long abx = bx - ax ;
    long aby = by - ay ;
    long px = x [ i ] - ax ;
    long py = y [ i ] - ay ;
    long qx = x [ 0 ] - ax ;
    long qy = y [ 0 ] - ay ;
    if ( i < N - 1 ) {
      qx = x [ i + 1 ] - ax ;
      qy = y [ i + 1 ] - ay ;
    }
    long ex = x [ 0 ] - x [ N - 1 ] ;
    long ey = y [ 0 ] - y [ N - 1 ] ;
    if ( i < N - 1 ) {
      ex = x [ i + 1 ] - x [ i ] ;
      ey = y [ i + 1 ] - y [ i ] ;
    }
    long rx = ax - x [ i ] ;
    long ry = ay - y [ i ] ;
    long sx = bx - x [ i ] ;
    long sy = by - y [ i ] ;
    if ( ( ( abx * py - aby * px ) * ( abx * qy - aby * qx ) <= 0 ) && ( ( ex * ry - ey * rx ) * ( ex * sy - ey * sx ) <= 0 ) ) count ++ ;
  }
  System . out . println ( count / 2 + 1 ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; long ax = sc . nextLong ( ) ; long ay = sc . nextLong ( ) ; long bx = sc . nextLong ( ) ; long by = sc . nextLong ( ) ; int N = sc . nextInt ( ) ; long [ ] x = new long [ N ] ; long [ ] y = new long [ N ] ; for ( int i = 0 ; i < N ; i ++ ) { x [ i ] = sc . nextLong ( ) ; y [ i ] = sc . nextLong ( ) ; } int count = 0 ; for ( int i = 0 ; i < N ; i ++ ) { long abx = bx - ax ; long aby = by - ay ; long px = x [ i ] - ax ; long py = y [ i ] - ay ; long qx = x [ 0 ] - ax ; long qy = y [ 0 ] - ay ; if ( i < N - 1 ) { qx = x [ i + 1 ] - ax ; qy = y [ i + 1 ] - ay ; } long ex = x [ 0 ] - x [ N - 1 ] ; long ey = y [ 0 ] - y [ N - 1 ] ; if ( i < N - 1 ) { ex = x [ i + 1 ] - x [ i ] ; ey = y [ i + 1 ] - y [ i ] ; } long rx = ax - x [ i ] ; long ry = ay - y [ i ] ; long sx = bx - x [ i ] ; long sy = by - y [ i ] ; if ( ( ( abx * py - aby * px ) * ( abx * qy - aby * qx ) <= 0 ) && ( ( ex * ry - ey * rx ) * ( ex * sy - ey * sx ) <= 0 ) ) count ++ ; } System . out . println ( count / 2 + 1 ) ; }
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object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (array_type element: (integral_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (identifier))))) (local_variable_declaration type: (array_type element: (integral_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (identifier))))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (block (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (block (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (identifier) right: (identifier)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (identifier) right: (identifier)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (identifier)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (identifier)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (array_access array: (identifier) index: (decimal_integer_literal)) right: (identifier)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (array_access array: (identifier) index: (decimal_integer_literal)) right: (identifier)))) (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (binary_expression left: (identifier) right: (decimal_integer_literal)))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (array_access array: (identifier) index: (binary_expression left: (identifier) right: (decimal_integer_literal))) right: (identifier)))) (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (array_access array: (identifier) index: (binary_expression left: (identifier) right: (decimal_integer_literal))) right: (identifier)))))) (local_variable_declaration type: 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