public static void main ( String ... args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int [ ] x = new int [ ] {
    sc . nextInt ( ) , sc . nextInt ( ) , sc . nextInt ( ) , sc . nextInt ( ) };
    int [ ] tl = new int [ 101 ] ;
    for ( int i = 0 ;
    i < 101 ;
    i ++ ) {
      if ( i >= x [ 0 ] && i < x [ 1 ] ) tl [ i ] ++ ;
      if ( i >= x [ 2 ] && i < x [ 3 ] ) tl [ i ] ++ ;
    }
    int ans = 0 ;
    for ( int i = 0 ;
    i < 101 ;
    i ++ ) {
      if ( tl [ i ] == 2 ) ans ++ ;
    }
    System . out . println ( ans ) ;
  }
  
public static void main ( String ... args ) { Scanner sc = new Scanner ( System . in ) ; int [ ] x = new int [ ] { sc . nextInt ( ) , sc . nextInt ( ) , sc . nextInt ( ) , sc . nextInt ( ) } ; int [ ] tl = new int [ 101 ] ; for ( int i = 0 ; i < 101 ; i ++ ) { if ( i >= x [ 0 ] && i < x [ 1 ] ) tl [ i ] ++ ; if ( i >= x [ 2 ] && i < x [ 3 ] ) tl [ i ] ++ ; } int ans = 0 ; for ( int i = 0 ; i < 101 ; i ++ ) { if ( tl [ i ] == 2 ) ans ++ ; } System . out . println ( ans ) ; }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (spread_parameter (type_identifier) (variable_declarator name: (identifier)))) body: (block (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (type_identifier) arguments: (argument_list (field_access object: (identifier) field: (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) value: (array_initializer (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) (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 (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: (decimal_integer_literal)) update: (update_expression (identifier)) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (array_access array: (identifier) index: (decimal_integer_literal))) right: (binary_expression left: (identifier) right: (array_access array: (identifier) index: (decimal_integer_literal))))) consequence: (expression_statement (update_expression (array_access array: (identifier) index: (identifier))))) (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (array_access array: (identifier) index: (decimal_integer_literal))) right: (binary_expression left: (identifier) right: (array_access array: (identifier) index: (decimal_integer_literal))))) consequence: (expression_statement (update_expression (array_access array: (identifier) index: (identifier))))))) (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: (decimal_integer_literal)) update: (update_expression (identifier)) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (decimal_integer_literal))) consequence: (expression_statement (update_expression (identifier)))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))