CREATE TABLE table_25691838_12 (episode__number INT, guest VARCHAR)

What is the episode # when the guests were julie nixon eisenhower and david eisenhower?
SELECT MIN(episode__number) FROM table_25691838_12 WHERE guest = "Julie Nixon Eisenhower and David Eisenhower"
SELECT MIN("episode__number") FROM "table_25691838_12" WHERE "Julie Nixon Eisenhower and David Eisenhower" = "guest"