How many next in lines had heirs of Archduke Karl?
CREATE TABLE "heirs_to_the_austrian_empire" (
  "emperor" text,
  "heir" text,
  "relationship_to_emperor_and_status" text,
  "became_heir" text,
  "ceased_to_be_heir" text,
  "next_in_line" text
);
SELECT COUNT("next_in_line") FROM "heirs_to_the_austrian_empire" WHERE "heir"='Archduke Karl';