Find the average age and number of male students (with sex M) from each city.
return cities ;return students from  #1 ;return sex of  #2 ;return #2 where #3 is  M ;return ages of  #4 ;return average of  #5 for each  #1 ;return number of  #4 for each  #1 ;return #6 ,  #7
['select', 'project', 'project', 'comparative', 'project', 'group', 'group', 'union']