Which country has both stadiums with capacity greater than 60000 and stadiums with capacity less than 50000?
return countries ;return stadiums of  #1 ;return capacities of  #2 ;return #1 where #2 is  higher than 60000 ;return #1 where #2 is  lower than 50000 ;return #1 of  both #4 and  #5
['select', 'project', 'project', 'comparative', 'comparative', 'intersection']