CREATE TABLE table_203_397 (id DECIMAL, "series" TEXT, "launch date" TEXT, "finale date" TEXT, "days" DECIMAL, "housemates" DECIMAL, "winner" TEXT, "main presenter" TEXT, "grand prize" TEXT, "liveshow\ audience\ millions" DECIMAL)

how many days was the longest season of grande fratello ?
SELECT MAX("days") FROM table_203_397
SELECT MAX("days") FROM "table_203_397"