On how many different dates did the episode directed by Marcos Siega and written by Scott Buck air for the first time?
CREATE TABLE "table1_24132083_1" (
  "no_in_series" real,
  "no_in_season" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "u_s_viewers_millions" text
);
SELECT COUNT("original_air_date") FROM "table1_24132083_1" WHERE "directed_by"='Marcos Siega' AND "written_by"='Scott Buck';