question: Did M2 star a actor , star M3 and M4 , and star M1 's employee
query: SELECT count(*) WHERE {
  ?x0 a ns:film.actor .
  ?x1 ns:people.person.employment_history/ns:business.employment_tenure.company M1 .
  M2 ns:film.film.starring/ns:film.performance.actor ?x0 .
  M2 ns:film.film.starring/ns:film.performance.actor ?x1 .
  M2 ns:film.film.starring/ns:film.performance.actor M3 .
  M2 ns:film.film.starring/ns:film.performance.actor M4
  }