Find the different first names and cities of the students who have allergy to milk or cat.
return students ;return #1 that  have  allergy to  milk ;return #1 that  have  allergy to  cat ;return #2 or  #3 ;return first names of  #4 ;return cities of  #4 ;return #5 ,   #6
['select', 'filter', 'filter', 'union', 'project', 'project', 'union']