question: Was M4 executive produced by a person that directed M1 , M2 , and M3
query: SELECT count(*) WHERE {
  ?x0 a ns:people.person .
  ?x0 ns:film.director.film M1 .
  ?x0 ns:film.director.film M2 .
  ?x0 ns:film.director.film M3 .
  M4 ns:film.film.executive_produced_by ?x0
  }