What is the sum of hours for projects that scientists with the name Michael Rogers or Carol Smith are assigned to?
return scientists ;return names of #1 ;return #1 where #2 is  Michael Rogers ;return #1 where #2 is  Carol Smith ;return #3 or  #4 ;return projects of #5 ;return hours of #6 ;return sum of #7
['select', 'project', 'comparative', 'comparative', 'union', 'project', 'project', 'aggregate']