Did M1 , M2 , M3 , and M4 executive produce a film 's sequel
SELECT count(*) WHERE {
?x0 ns:film.film.prequel ?x1 .
?x1 a ns:film.film .
M1 ns:film.producer.films_executive_produced ?x0 .
M2 ns:film.producer.films_executive_produced ?x0 .
M3 ns:film.producer.films_executive_produced ?x0 .
M4 ns:film.producer.films_executive_produced ?x0
}