CREATE TABLE table_203_780 (id DECIMAL, "rank" DECIMAL, "diver" TEXT, "preliminary\ points" DECIMAL, "preliminary\ rank" DECIMAL, "final\ points" DECIMAL, "final\ rank" DECIMAL, "final\ total" DECIMAL)

how many divers were involved in the preliminary round but not the final ?
SELECT COUNT("diver") FROM table_203_780 WHERE NOT "preliminary\nrank" IS NULL AND "final\nrank" IS NULL
SELECT COUNT("diver") FROM "table_203_780" WHERE "final\nrank" IS NULL AND NOT "preliminary\nrank" IS NULL