Please give me a list of cities whose regional population is over 8000000 or under 5000000.
return cities ;return regional populations of  #1 ;return #1 where #2 is  higher than 8000000 ;return #1 where #2 is  lower than 5000000 ;return #3 or  #4
['select', 'project', 'comparative', 'comparative', 'union']