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_20 (extra_points INTEGER, points VARCHAR, field_goals VARCHAR)
### Question:
What is the highest amount of extra points someone got when they scored 28 points but had 0 field goals?
### Answer:
SELECT MAX(extra_points) FROM table_name_20 WHERE points = 28 AND field_goals < 0