What are the ids of suppliers which have an average amount purchased of above 50000 or below 30000?
return suppliers ;return amounts purchased of  #1 ;return average of  #2 for each  #1 ;return #1 where #3 is  higher than 50000 ;return #1 where #3 is  lower than 30000 ;return #4 or  #5 ;return ids of  #6
['select', 'project', 'group', 'comparative', 'comparative', 'union', 'project']