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_10 (goal_difference INTEGER, club VARCHAR, wins VARCHAR)
### Question:
What is the lowest goal difference of club real betis, who has less than 18 wins?
### Answer:
SELECT MIN(goal_difference) FROM table_name_10 WHERE club = "real betis" AND wins < 18