bbb bbk bbn bbo bbr bbs bkb bkk bkn bko bkr bks bnb bnk bnn bno bnr bns bob bok bon boo bor bos brb brk brn bro brr brs bsb bsk bsn bso bsr bss kbb kbk kbn kbo kbr kbs kkb kkk kkn kkr kks kn- knk knn kno knr kob kok kon koo kor kos krk krn kro krr krs ksb ksk ksn kso ksr kss nbb nbk nbn nbo nbr nbs nkk nkn nko nkr nks nnb nnk nnn nno nns no- nob nok non noo nor nos nrb nrk nrn nro nrr nrs nsb nsk nsn nso nsr nss ob- obb obk obn obo obr obs okb okk oko okr oks on- onb onk onn ono onr ons oo- oob ook oon ooo oor oos or- orb ork orn oro orr ors os- osb osk osn oso osr oss rbb rbk rbn rbo rbr rbs rkb rkk rko rks rnb rnn rno rnr rns rob rok ron roo ror ros rrb rrk rrn rrr rrs rsb rsk rsn rso rsr rss sbb sbk sbn sbo sbr sbs sk- skb skk sko skr sks snb snk snn sno snr sns sob sok son soo sor sos sr- srb srk srn sro srr srs ss- ssb ssk ssn sso ssr sss