Find the name of the ships that are steered by both a captain with Midshipman rank and a captain with Lieutenant rank.
select t1.name from ship as t1 join captain as t2 on t1.ship_id = t2.ship_id where t2.rank = 'Midshipman' intersect select t1.name from ship as t1 join captain as t2 on t1.ship_id = t2.ship_id where t2.rank = 'Lieutenant'