Was a film 's sequel written by M0 and directed by M1 and M2
SELECT count(*) WHERE {
?x0 ns:film.film.directed_by M1 .
?x0 ns:film.film.directed_by M2 .
?x0 ns:film.film.prequel ?x1 .
?x0 ns:film.film.written_by M0 .
?x1 a ns:film.film
}