How many votes passed are listed on the measure that had 390338 yes votes? 
CREATE TABLE "1956_general_election" (
  "meas_num" real,
  "passed" text,
  "yes_votes" real,
  "no_votes" real,
  "pct_yes" text,
  "const_amd" text,
  "type" text,
  "description" text
);
SELECT COUNT("passed") FROM "1956_general_election" WHERE "yes_votes"=390338;