How many restaurants with the highest risk level still passed the inspection?
restaurant refers to facility_type = 'Restaurant'; the highest risk level refers to max(risk_level); pass the inspection refers to results = 'Pass'
SELECT COUNT(DISTINCT T1.license_no) FROM establishment AS T1 INNER JOIN inspection AS T2 ON T1.license_no = T2.license_no WHERE T1.risk_level = 3 AND T2.results = 'Pass' AND T1.facility_type = 'Restaurant'