b-u bbb bbc bbg bbk bbo bbr bbs bbt bbu bcb bcc bcg bck bco bcr bcs bct bcu bgb bgc bgg bgk bgo bgr bgs bgt bgu bkb bkc bkg bkk bko bkr bks bkt bob boc bog bok boo bor bos bot bou brb brg brk bro brr brs brt bru bsb bsc bsg bsk bso bsr bss bst bsu btb btc btg btk bto btr bts btt btu bub buc bug buk buo bur bus but buu c-- cbb cbc cbg cbk cbo cbr cbs cbt cbu ccb ccc ccg cck cco ccr ccs cct ccu cgb cgc cgg cgo cgr cgs cgt cgu ckb ckc cko cks ckt co- cob coc cog cok coo cor cos cot cou crb crc crg crk cro crr crs crt cru csb csc csg csk cso csr css cst csu ctb ctc ctg ctk cto ctr cts ctt ctu cub cuc cug cuk cuo cur cus cut cuu gbc gbg gbk gbo gbr gbs gbt gbu gcb gcc gcg gck gco gcr gcs gct gcu ggb ggc ggg ggo ggr ggs ggt ggu gkb gko gks gkt gob goc gog gok goo gor gos got gou grb grc grg grk gro grr grs grt gru gsb gsc gsg gsk gso gsr gss gst gsu gtb gtc gtg gtk gto gtr gts gtt gtu gu- gub guc gug guk guo gur gus gut guu k-t kbb kbc kbk kbo kbr kbs kbu kcb kcc kcg kck kcr kcs kct kcu kgb kgc kgo kgs kgu kkb kkc kkk kkr kks kkt kku kob koc kog kok koo kor kos kot kou krc krg krk kro krr krs krt kru ksb ksc ksg ksk kso ksr kss kst ksu ktb ktc ktg ktk kto ktr kts ktt ktu kub kuc kug kuk kur kus kut kuu ob- obb obc obg obk obo obr obs obt obu oc- ocb occ ocg ock oco ocr ocs oct ocu ogc ogg ogo ogs ogt okb okc okg okk oko okr oks oku oo- oob ooc oog ook ooo oor oos oot or- orb orc org ork oro orr ors ort oru os- osb osc osg osk oso osr oss ost osu ot- otb otc otg otk oto otr ots ott otu ou- ouc ouk ouo our ous out rbb rbc rbg rbk rbo rbr rbs rbt rbu rcb rcc rcg rco rcr rcs rct rcu rgb rgc rgg rgk rgo rgr rgs rgt rkb rkc rkg rkk rko rks rkt rku rob roc rog rok roo ror ros rot rou rrb rrc rrg rrk rrr rrs rrt rru rsb rsc rsg rsk rso rsr rss rst rsu rtb rtc rtg rtk rto rtr rts rtt rtu rub ruc rug ruk ruo rur rus rut ruu sbb sbc sbg sbk sbo sbr sbs sbt sbu scb scc scg sck sco scr scs sct scu sgb sgc sgg sgk sgo sgr sgs sgt sgu sk- skb skc skg skk sko skr sks skt sku sob soc sog sok soo sor sos sot sou sr- srb src srg srk sro srr srs srt ss- ssb ssc ssg ssk sso ssr sss sst ssu stb stc stg stk sto str sts stt stu sub suc sug suk suo sur sus sut suu tbb tbc tbg tbk tbo tbr tbs tbt tbu tcb tcc tcg tck tco tcr tcs tct tcu tgb tgc tgg tgk tgo tgr tgs tgt tgu tkb tkc tkg tkk tko tkr tks tkt to- tob toc tog tok too tor tos tot tou trb trc trg trk tro trr trs trt tru tsb tsc tsg tsk tso tsr tss tst tsu ttb ttc ttg ttk tto ttr tts ttt ttu tub tuc tug tuk tuo tur tus tut tuu ubb ubc ubg ubk ubo ubr ubs ubt ubu ucb ucc ucg uck uco ucr ucs uct ucu ugb ugc ugg ugk ugo ugr ugs ugt ugu ukb ukc ukk ukr uku uob uoc uog uok uoo uor uos uot ur- urb urc urg urk uro urr urs urt uru usb usc usg usk uso usr uss ust usu utb utc utk uto utr uts utt utu uuc uug uur uus uut uuu