Were M2 , M3 , M4 , M5 , and M6 written by a Mexican director of M1
SELECT count(*) WHERE {
?x0 ns:film.director.film M1 .
?x0 ns:people.person.nationality ns:m.0b90_r .
M2 ns:film.film.written_by ?x0 .
M3 ns:film.film.written_by ?x0 .
M4 ns:film.film.written_by ?x0 .
M5 ns:film.film.written_by ?x0 .
M6 ns:film.film.written_by ?x0
}