How many different departments are there in each school that has less than 5 apartments?
return schools ;return apartments of  #1 ;return number of #2 for each #1 ;return #1 where  #3 is  lower than 5 ;return departments of  #4 ;return different #5 ;return number of #6
['select', 'project', 'group', 'comparative', 'project', 'project', 'aggregate']