Question: Find the number of students who are older than 18 and do not have allergy to either food or animal.
SQL: SELECT count(*) FROM Student WHERE age  >  18 AND StuID NOT IN ( SELECT StuID FROM Has_allergy AS T1 JOIN Allergy_Type AS T2 ON T1.Allergy  =  T2.Allergy WHERE T2.allergytype  =  "food" OR T2.allergytype  =  "animal")