What is the average prominence in m of pietrosul rodnei peak, which has an elevation less than 2,303?
CREATE TABLE "list_of_european_ultra_prominent_peaks" (
  "peak" text,
  "country" text,
  "elevation_m" real,
  "prominence_m" real,
  "col_m" real
);
SELECT AVG("prominence_m") FROM "list_of_european_ultra_prominent_peaks" WHERE "peak"='pietrosul rodnei' AND "elevation_m"<'2,303';