CREATE TABLE captain (captain_id DECIMAL, name TEXT, ship_id DECIMAL, age TEXT, class TEXT, rank TEXT)
CREATE TABLE ship (ship_id DECIMAL, name TEXT, type TEXT, built_year DECIMAL, class TEXT, flag TEXT)

Find the ship type that are used by both ships with Panama and Malta flags.
SELECT type FROM ship WHERE flag = 'Panama' INTERSECT SELECT type FROM ship WHERE flag = 'Malta'
SELECT "type" FROM "ship" WHERE "flag" = 'Panama' INTERSECT SELECT "type" FROM "ship" WHERE "flag" = 'Malta'