Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_15 (mountains_classification VARCHAR, general_classification VARCHAR, winner VARCHAR)
### Question:
What's the mountains classification of winner Carlos Sastre when the general classification is Denis Menchov?
### Answer:
SELECT mountains_classification FROM table_name_15 WHERE general_classification = "denis menchov" AND winner = "carlos sastre"