Were M1 and M3 directed by a film editor , written by M2 , and edited by a film editor
SELECT count(*) WHERE {
?x0 a ns:film.editor .
?x1 a ns:film.editor .
M1 ns:film.film.directed_by ?x1 .
M1 ns:film.film.edited_by ?x0 .
M1 ns:film.film.written_by M2 .
M3 ns:film.film.directed_by ?x1 .
M3 ns:film.film.edited_by ?x0 .
M3 ns:film.film.written_by M2
}