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")
Find the number of students who are older than 18 and do not have allergy to either food or animal.
[Schema (values) (types)]: | allergy_1 |  Allergy_Type : allergy (text) , allergytype (text) | Has_Allergy : stuid (text) , allergy (text) | Student : stuid (text) , lname (text) , fname (text) , age (number) , sex (text) , major (number) , advisor (text) , city_code (text);