Were M1 and M4 directed by M2 and M3 and directed by a actor
SELECT count(*) WHERE {
?x0 a ns:film.actor .
M1 ns:film.film.directed_by ?x0 .
M1 ns:film.film.directed_by M2 .
M1 ns:film.film.directed_by M3 .
M4 ns:film.film.directed_by ?x0 .
M4 ns:film.film.directed_by M2 .
M4 ns:film.film.directed_by M3
}