bbb bbh bbo bbr bbs bhb bhh bho bhr bhs bob boh boo bor bos brb brh bro brr brs bsb bsh bso bsr bss hbb hbh hbo hbr hbs hhb hhh hho hhr hhs hob hoh hoo hor hos hr- hrb hrh hro hrr hrs hsb hsh hsr hss ob- obb obh obo obr obs ohh oho ohr ohs oo- oob ooh ooo oor oos or- orb orh oro orr ors os- osb osh oso osr oss rbb rbh rbo rbr rbs rh- rhb rhh rho rhr rhs rob roh roo ror ros rrb rrh rrr rrs rsb rsh rso rsr rss sbb sbh sbo sbr sbs sh- shb shh sho shr shs sob soh soo sor sos sr- srb srh sro srr srs ss- ssb ssh sso ssr sss