Did M3 and M4 employ a Mexican actor that wrote M1
SELECT count(*) WHERE {
?x0 a ns:film.actor .
?x0 ns:film.writer.film M1 .
?x0 ns:people.person.nationality ns:m.0b90_r .
M3 ns:business.employer.employees/ns:business.employment_tenure.person ?x0 .
M4 ns:business.employer.employees/ns:business.employment_tenure.person ?x0
}