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_21 (laps INTEGER, time_retired VARCHAR, grid VARCHAR)
### Question:
Tell me the sum of laps with a time/retired of +13 laps with grid more than 18
### Answer:
SELECT SUM(laps) FROM table_name_21 WHERE time_retired = "+13 laps" AND grid > 18