How many states that have some college students playing in the mid position but not in the goalie position.
return college students ;return positions of  #1 ;return #1 where  #2 is mid ;return #1 where  #2 is not  goalie ;return #1 of  both #3 and #4 ;return states of  #5
['select', 'project', 'comparative', 'comparative', 'intersection', 'project']