bbbb bbdd bbpr bd-r bdii bibb bibi bidi bidr bidu bipp bipu birb bird biri birr biru bprd brid brrr brud brup bubb bubi bubu budb budd budi budu buid buir buiu bur- burb burd buri burp burr buru dbpd dddd ddub dibb dibp didi didu diii dipp dipu dird dirr drib drip drub drui drup druu dub- dubb dubu dudd dudu duid duir duri duru duur ibid ibrd ibri idid idir idub iiii ipdi ipid ippr ipri ipur irbp irdp iri- irid irip irri iuiu iupp pdpr pibb pibi piip pipi pipp piri pirr piru ppib ppid pppd pppp ppru ppur pri- prid prii prpd prrd prri prud pruu pubu pudu puid puir puiu pupi pupu pur- purb puri purp purr puru rbbb rbbr rdbp rib- ribu ridd ridi ripd ripi ripp ripr riri rpdp rpii rrrr rubb rubi rubp rubu rudd rudi rudp ruid rupp rurd ruri rurp ruru ruud u-rp ubbi ubid ubii ubir ubud uddi udid udir udpd uipi uirr uppp uppu upri upup urbi urdu urib uriu urri urup urur uuri uuuu