What is the least 3rd RU that is ranked less than 8 with a 4th RU greater than 0?
CREATE TABLE "by_country_tally" (
  "rank" real,
  "country" text,
  "miss_united_continent" real,
  "virreina" real,
  "1st_ru" real,
  "2nd_ru" real,
  "3rd_ru" real,
  "4th_ru" real,
  "semifinalists" real,
  "total" real
);
SELECT MIN("3rd_ru") FROM "by_country_tally" WHERE "4th_ru">0 AND "rank"<8;