What is the lowest roll number of Katikati college?
CREATE TABLE "western_bay_of_plenty_district" (
  "name" text,
  "years" text,
  "gender" text,
  "area" text,
  "authority" text,
  "decile" real,
  "roll" real
);
SELECT MIN("roll") FROM "western_bay_of_plenty_district" WHERE "name"='katikati college';