SQL query using SET operator

Using a SET command, show all the countries in region 1 that do not have a location. Display only the country_id.

This is my query and it's wrong. I can't figure it out.

SELECT c.country_id
FROM Countries c
WHERE r.region_id = 1
MINUS
SELECT c2.country_id
FROM Countries c2
WHERE l.location_id IS NULL;




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