What are the first names of all students taking accoutning and Computer Information Systems classes?
return students ;return classes #1 are  taking ;return #1 where #2 is  accoutning ;return #1 where #2 is  Computer Information Systems ;return #1 of  both #3 and  #4 ;return first names of  #5
['select', 'project', 'comparative', 'comparative', 'intersection', 'project']