Find the first name and gender of the student who has allergy to milk but not cat.
SELECT fname ,  sex FROM Student WHERE StuID IN (SELECT StuID FROM Has_allergy WHERE Allergy  =  "Milk" EXCEPT SELECT StuID FROM Has_allergy WHERE Allergy  =  "Cat")
Süt alerjisi olan ancak kedi olmayan öğrencinin adını ve cinsiyetini bulun.