Question: What is the count of states with college students playing in the mid position but not as goalies?
SQL: 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')