Did M1 and M4 direct a film 's prequel and sequel and direct M2 and M3
SELECT count(*) WHERE {
?x0 ns:film.film.prequel ?x1 .
?x0 ns:film.film.sequel ?x1 .
?x1 a ns:film.film .
M1 ns:film.director.film ?x0 .
M1 ns:film.director.film M2 .
M1 ns:film.director.film M3 .
M4 ns:film.director.film ?x0 .
M4 ns:film.director.film M2 .
M4 ns:film.director.film M3
}