Was a American star of a film whose prequel starred M1 M2
SELECT count(*) WHERE {
?x0 a ns:film.film .
?x0 ns:film.film.prequel ?x1 .
?x1 ns:film.film.starring/ns:film.performance.actor M1 .
M2 ns:film.actor.film/ns:film.performance.film ?x0 .
M2 ns:people.person.nationality ns:m.09c7w0
}