question: Were M4 and M6 directed by a Canadian film editor that wrote M1 and M2 and directed by M5
query: SELECT count(*) WHERE {
  ?x0 a ns:film.editor .
  ?x0 ns:film.writer.film M1 .
  ?x0 ns:film.writer.film M2 .
  ?x0 ns:people.person.nationality ns:m.0d060g .
  M4 ns:film.film.directed_by ?x0 .
  M4 ns:film.film.directed_by M5 .
  M6 ns:film.film.directed_by ?x0 .
  M6 ns:film.film.directed_by M5
  }