Find the total hours of the projects that scientists named Michael Rogers or Carol Smith are assigned to.
return scientists ;return projects of  #1 ;return #2 where  #1 is  Michael Rogers ;return #2 where  #1 is  Carol Smith ;return #3 or  #4 ;return hours of  #5 ;return sum of  #6
['select', 'project', 'comparative', 'comparative', 'union', 'project', 'aggregate']