public static void main ( String [ ] args ) {
  int n , m , count = 0 ;
  ;
  Scanner in = new Scanner ( System . in ) ;
  Set < Integer > set = new HashSet < Integer > ( ) ;
  n = in . nextInt ( ) ;
  m = in . nextInt ( ) ;
  int l [ ] = new int [ n ] ;
  int r [ ] = new int [ n ] ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    l [ i ] = in . nextInt ( ) ;
    r [ i ] = in . nextInt ( ) ;
    for ( int j = l [ i ] ;
    j <= r [ i ] ;
    j ++ ) {
      set . add ( j ) ;
    }
  }
  for ( int i = 1 ;
  i <= m ;
  i ++ ) {
    if ( ! set . contains ( i ) ) {
      count ++ ;
    }
  }
  System . out . println ( count ) ;
  for ( int i = 1 ;
  i <= m ;
  i ++ ) {
    if ( ! set . contains ( i ) ) {
      System . out . print ( i + " " ) ;
    }
  }
}

public static void main ( String [ ] args ) { int n , m , count = 0 ; ; Scanner in = new Scanner ( System . in ) ; Set < Integer > set = new HashSet < Integer > ( ) ; n = in . nextInt ( ) ; m = in . nextInt ( ) ; int l [ ] = new int [ n ] ; int r [ ] = new int [ n ] ; for ( int i = 0 ; i < n ; i ++ ) { l [ i ] = in . nextInt ( ) ; r [ i ] = in . nextInt ( ) ; for ( int j = l [ i ] ; j <= r [ i ] ; j ++ ) { set . add ( j ) ; } } for ( int i = 1 ; i <= m ; i ++ ) { if ( ! set . contains ( i ) ) { count ++ ; } } System . out . println ( count ) ; for ( int i = 1 ; i <= m ; i ++ ) { if ( ! set . contains ( i ) ) { 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: (integral_type) declarator: (variable_declarator name: (identifier)) declarator: (variable_declarator name: (identifier)) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (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: (generic_type (type_identifier) (type_arguments (type_identifier))) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (generic_type (type_identifier) (type_arguments (type_identifier))) arguments: (argument_list)))) (expression_statement (assignment_expression left: (identifier) right: (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)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) dimensions: (dimensions) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (identifier))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) dimensions: (dimensions) 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)))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (array_access array: (identifier) index: (identifier)))) condition: (binary_expression left: (identifier) right: (array_access array: (identifier) index: (identifier))) update: (update_expression (identifier)) body: (block (expression_statement (method_invocation object: (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: (block (if_statement condition: (parenthesized_expression (unary_expression operand: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))) consequence: (block (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: (block (if_statement condition: (parenthesized_expression (unary_expression operand: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))) consequence: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (string_literal)))))))))))