what is the lowest height (ft) for messeturm and more than 55 floors?
CREATE TABLE "tallest_buildings" (
  "rank" real,
  "name" text,
  "city" text,
  "height_m" real,
  "height_ft" real,
  "floors" real
);
SELECT MIN("height_ft") FROM "tallest_buildings" WHERE "name"='messeturm' AND "floors">55;