b-u bbb bbc bbk bbo bbs bbt bbu bcb bcc bck bco bcs bct bcu bkb bkc bkk bko bks bkt bob boc bok boo bos bot bou bsb bsc bsk bso bss bst bsu btb btc btk bto bts btt btu bub buc buk buo bus but buu c-- cbb cbc cbk cbo cbs cbt cbu ccb ccc cck cco ccs cct ccu ckb ckc cko cks ckt co- cob coc cok coo cos cot cou csb csc csk cso css cst csu ctb ctc ctk cto cts ctt ctu cub cuc cuk cuo cus cut cuu k-t kbb kbc kbk kbo kbs kbu kcb kcc kck kcs kct kcu kkb kkc kkk kks kkt kku kob koc kok koo kos kot kou ksb ksc ksk kso kss kst ksu ktb ktc ktk kto kts ktt ktu kub kuc kuk kus kut kuu ob- obb obc obk obo obs obt obu oc- ocb occ ock oco ocs oct ocu okb okc okk oko oks oku oo- oob ooc ook ooo oos oot os- osb osc osk oso oss ost osu ot- otb otc otk oto ots ott otu ou- ouc ouk ouo ous out sbb sbc sbk sbo sbs sbt sbu scb scc sck sco scs sct scu sk- skb skc skk sko sks skt sku sob soc sok soo sos sot sou ss- ssb ssc ssk sso sss sst ssu stb stc stk sto sts stt stu sub suc suk suo sus sut suu tbb tbc tbk tbo tbs tbt tbu tcb tcc tck tco tcs tct tcu tkb tkc tkk tko tks tkt to- tob toc tok too tos tot tou tsb tsc tsk tso tss tst tsu ttb ttc ttk tto tts ttt ttu tub tuc tuk tuo tus tut tuu ubb ubc ubk ubo ubs ubt ubu ucb ucc uck uco ucs uct ucu ukb ukc ukk uku uob uoc uok uoo uos uot usb usc usk uso uss ust usu utb utc utk uto uts utt utu uuc uus uut uuu