What is the lowest Points when against is 50, and there are less than 20 played?
CREATE TABLE "campeonato_paulista" (
  "position" real,
  "team" text,
  "points" real,
  "played" real,
  "drawn" real,
  "lost" real,
  "against" real,
  "difference" text
);
SELECT MIN("points") FROM "campeonato_paulista" WHERE "against"=50 AND "played"<20;