b-u bbb bbc bbk bbn bbo bbr bbs bbu bcb bcc bck bcn bco bcr bcs bcu bkb bkc bkk bkn bko bkr bks bnb bnc bnk bnn bno bnr bns bnu bob boc bok bon boo bor bos bou brb brk brn bro brr brs bru bsb bsc bsk bsn bso bsr bss bsu bub buc buk bun buo bur bus buu c-- cbb cbc cbk cbn cbo cbr cbs cbu ccb ccc cck ccn cco ccr ccs ccu ckb ckc cko cks cn- cnb cnc cnn cno cnr cns cnu co- cob coc cok con coo cor cos cou crb crc crk crn cro crr crs cru csb csc csk csn cso csr css csu cub cuc cuk cun cuo cur cus cuu kbb kbc kbk kbn kbo kbr kbs kbu kcb kcc kck kcn kcr kcs kcu kkb kkc kkk kkn kkr kks kku kn- knc knk knn kno knr knu kob koc kok kon koo kor kos kou krc krk krn kro krr krs kru ksb ksc ksk ksn kso ksr kss ksu kub kuc kuk kun kur kus kuu nbb nbc nbk nbn nbo nbr nbs nbu ncb ncc nck ncn nco ncr ncs ncu nkc nkk nkn nko nkr nks nku nnb nnc nnk nnn nno nns nnu no- nob noc nok non noo nor nos nou nrb nrc nrk nrn nro nrr nrs nru nsb nsc nsk nsn nso nsr nss nsu nub nuc nuk nun nuo nur nus nuu ob- obb obc obk obn obo obr obs obu oc- ocb occ ock ocn oco ocr ocs ocu okb okc okk oko okr oks oku on- onb onc onk onn ono onr ons onu oo- oob ooc ook oon ooo oor oos or- orb orc ork orn oro orr ors oru os- osb osc osk osn oso osr oss osu ou- ouc ouk oun ouo our ous rbb rbc rbk rbn rbo rbr rbs rbu rcb rcc rcn rco rcr rcs rcu rkb rkc rkk rko rks rku rnb rnc rnn rno rnr rns rnu rob roc rok ron roo ror ros rou rrb rrc rrk rrn rrr rrs rru rsb rsc rsk rsn rso rsr rss rsu rub ruc ruk run ruo rur rus ruu sbb sbc sbk sbn sbo sbr sbs sbu scb scc sck scn sco scr scs scu sk- skb skc skk sko skr sks sku snb snc snk snn sno snr sns snu sob soc sok son soo sor sos sou sr- srb src srk srn sro srr srs ss- ssb ssc ssk ssn sso ssr sss ssu sub suc suk sun suo sur sus suu ubb ubc ubk ubn ubo ubr ubs ubu ucb ucc uck ucn uco ucr ucs ucu ukb ukc ukk ukn ukr uku un- unb unc unk unn uno unr uns unu uob uoc uok uon uoo uor uos ur- urb urc urk urn uro urr urs uru usb usc usk usn uso usr uss usu uuc uun uur uus uuu