question: Were M4 and M6 employed by M5 and employed by a production company whose employee wrote M1 , M2 , and M3
query: SELECT count(*) WHERE {
  ?x0 a ns:film.production_company .
  ?x0 ns:business.employer.employees/ns:business.employment_tenure.person ?x1 .
  ?x1 ns:film.writer.film M1 .
  ?x1 ns:film.writer.film M2 .
  ?x1 ns:film.writer.film M3 .
  M4 ns:people.person.employment_history/ns:business.employment_tenure.company ?x0 .
  M4 ns:people.person.employment_history/ns:business.employment_tenure.company M5 .
  M6 ns:people.person.employment_history/ns:business.employment_tenure.company ?x0 .
  M6 ns:people.person.employment_history/ns:business.employment_tenure.company M5
  }