Were M2 and M3 directed by a film 's writer and directed by a art director
SELECT count(*) WHERE {
?x0 ns:film.writer.film ?x1 .
?x1 a ns:film.film .
?x2 a ns:film.film_art_director .
M2 ns:film.film.directed_by ?x0 .
M2 ns:film.film.directed_by ?x2 .
M3 ns:film.film.directed_by ?x0 .
M3 ns:film.film.directed_by ?x2
}