public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  int m = sc . nextInt ( ) ;
  int a [ ] = new int [ m + 2 ] ;
  while ( n -- > 0 ) {
    int l = sc . nextInt ( ) ;
    int r = sc . nextInt ( ) ;
    for ( int i = l ;
    i <= r ;
    i ++ ) a [ i ] = 1 ;
  }
  int cnt = 0 ;
  for ( int i = 1 ;
  i <= m ;
  i ++ ) if ( a [ i ] == 0 ) cnt ++ ;
  System . out . println ( cnt ) ;
  for ( int i = 1 ;
  i <= m ;
  i ++ ) if ( a [ i ] == 0 ) System . out . print ( i + " " ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; int m = sc . nextInt ( ) ; int a [ ] = new int [ m + 2 ] ; while ( n -- > 0 ) { int l = sc . nextInt ( ) ; int r = sc . nextInt ( ) ; for ( int i = l ; i <= r ; i ++ ) a [ i ] = 1 ; } int cnt = 0 ; for ( int i = 1 ; i <= m ; i ++ ) if ( a [ i ] == 0 ) cnt ++ ; System . out . println ( cnt ) ; for ( int i = 1 ; i <= m ; i ++ ) if ( a [ i ] == 0 ) System . out . print ( i + " ▁ " ) ; }
(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)))) (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) dimensions: (dimensions) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (binary_expression left: (identifier) right: (decimal_integer_literal)))))) (while_statement condition: (parenthesized_expression (binary_expression left: (update_expression (identifier)) right: (decimal_integer_literal))) body: (block (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)))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (identifier))) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (decimal_integer_literal)))))) (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: (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)))) (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: (if_statement condition: (parenthesized_expression (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (decimal_integer_literal))) consequence: (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (string_literal)))))))))