question: Did M5 , M6 , and M7 produce a film that starred M1 , M2 , M3 , and M4
query: SELECT count(*) WHERE {
  ?x0 a ns:film.film .
  ?x0 ns:film.film.starring/ns:film.performance.actor M1 .
  ?x0 ns:film.film.starring/ns:film.performance.actor M2 .
  ?x0 ns:film.film.starring/ns:film.performance.actor M3 .
  ?x0 ns:film.film.starring/ns:film.performance.actor M4 .
  M5 ns:film.producer.film|ns:film.production_company.films ?x0 .
  M6 ns:film.producer.film|ns:film.production_company.films ?x0 .
  M7 ns:film.producer.film|ns:film.production_company.films ?x0
  }