What is the count of states with college students playing in the mid position but not as goalies?
SELECT COUNT(*) FROM (SELECT T1.state FROM college AS T1 JOIN tryout AS T2 ON T1.cName  =  T2.cName WHERE T2.pPos  =  'mid' EXCEPT SELECT T1.state FROM college AS T1 JOIN tryout AS T2 ON T1.cName  =  T2.cName WHERE T2.pPos  =  'goalie')
Üniversite öğrencilerinin orta pozisyonda oynadığı, ancak kaleciler olarak oynamasıyla devletlerin sayısı nedir?