public static void main ( String [ ] args ) {
  Scanner in = new Scanner ( System . in ) ;
  int n = in . nextInt ( ) , i , x = 0 , y = 0 , o = 1 ;
  for ( i = 0 ;
  i < n ;
  i ++ ) {
    int a = in . nextInt ( ) , b = in . nextInt ( ) ;
    o += Math . max ( 0 , Math . min ( a , b ) - Math . max ( x , y ) + ( x != y ? 1 : 0 ) ) ;
    x = a ;
    y = b ;
  }
  in . close ( ) ;
  System . out . println ( o ) ;
}

public static void main ( String [ ] args ) { Scanner in = new Scanner ( System . in ) ; int n = in . nextInt ( ) , i , x = 0 , y = 0 , o = 1 ; for ( i = 0 ; i < n ; i ++ ) { int a = in . nextInt ( ) , b = in . nextInt ( ) ; o += Math . max ( 0 , Math . min ( a , b ) - Math . max ( x , y ) + ( x != y ? 1 : 0 ) ) ; x = a ; y = b ; } in . close ( ) ; System . out . println ( o ) ; }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (array_type element: (type_identifier) dimensions: (dimensions)) 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: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) declarator: (variable_declarator name: (identifier)) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal)) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal)) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (for_statement init: (assignment_expression left: (identifier) right: (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: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (decimal_integer_literal) (binary_expression left: (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (identifier))) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (identifier)))) right: (parenthesized_expression (ternary_expression condition: (binary_expression left: (identifier) right: (identifier)) consequence: (decimal_integer_literal) alternative: (decimal_integer_literal)))))))) (expression_statement (assignment_expression left: (identifier) right: (identifier))) (expression_statement (assignment_expression left: (identifier) right: (identifier))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))