What are the maximum and minimum age of students with major 600?
return students ;return major of  #1 ;return #1 where #2 is  600 ;return ages of  #3 ;return maximum of  #4 ;return minimum of  #4 ;return #5 ,  #6
['select', 'project', 'comparative', 'project', 'aggregate', 'aggregate', 'union']