Which students participate in both Canoeing and Kayaking as their activities? Tell me their student ids.
return students ;return activities of  #1 ;return #1 where #2 is  Canoeing ;return #1 where #2 is  Kayaking ;return #1 of  both #3 and  #4 ;return student ids of  #5
['select', 'project', 'comparative', 'comparative', 'intersection', 'project']