question: Was a director and writer of M1 , M2 , and M3 a screenwriter
query: SELECT count(*) WHERE {
  ?x0 a ns:film.writer .
  ?x0 ns:film.director.film M1 .
  ?x0 ns:film.director.film M2 .
  ?x0 ns:film.director.film M3 .
  ?x0 ns:film.writer.film M1 .
  ?x0 ns:film.writer.film M2 .
  ?x0 ns:film.writer.film M3
  }