Were M2 and M4 employed by a production company , employed by M1 's producer , and employed by M3
SELECT count(*) WHERE {
?x0 a ns:film.production_company .
?x1 ns:film.producer.film|ns:film.production_company.films M1 .
M2 ns:people.person.employment_history/ns:business.employment_tenure.company ?x0 .
M2 ns:people.person.employment_history/ns:business.employment_tenure.company ?x1 .
M2 ns:people.person.employment_history/ns:business.employment_tenure.company M3 .
M4 ns:people.person.employment_history/ns:business.employment_tenure.company ?x0 .
M4 ns:people.person.employment_history/ns:business.employment_tenure.company ?x1 .
M4 ns:people.person.employment_history/ns:business.employment_tenure.company M3
}