How many chapters did Elmer Clifton direct?
CREATE TABLE "list_of_film_serials_by_studio" (
  "number" real,
  "serial_title" text,
  "year" real,
  "chapters" real,
  "genre" text,
  "director" text,
  "cast" text
);
SELECT COUNT("chapters") FROM "list_of_film_serials_by_studio" WHERE "director"='elmer clifton';