question: Was a person a film director that M2 , M3 , and M4 were executive produced by
query: SELECT count(*) WHERE {
  ?x0 a ns:film.director .
  ?x0 a ns:people.person .
  ?x0 ns:film.producer.films_executive_produced M2 .
  ?x0 ns:film.producer.films_executive_produced M3 .
  ?x0 ns:film.producer.films_executive_produced M4
  }