-ic bbb bbc bbi bbk bbo bbs bbt bcb bcc bci bck bco bcs bct bi- bib bic bii bik bio bis bit bkb bkc bkk bko bks bkt bob boc boi bok boo bos bot bsb bsc bsi bsk bso bss bst btb btc bti btk bto bts btt c-- cbb cbc cbi cbk cbo cbs cbt ccb ccc cci cck cco ccs cct ci- cib cic cii cik cio cis cit ckb ckc cki cko cks ckt co- cob coc coi cok coo cos cot csb csc csi csk cso css cst ctb ctc cti ctk cto cts ctt ibb ibc ibi ibk ibo ibs ibt icb icc ici ick ico ics ict iib iic iii iio iis iit ikb ikc iki ikk iko iks ikt io- iob ioc ioi ioo ios iot is- isb isc isi isk iso iss ist itb itc iti itk ito its itt k-t kbb kbc kbi kbk kbo kbs kcb kcc kci kck kcs kct kib kic kii kik kio kis kit kkb kkc kki kkk kks kkt kob koc koi kok koo kos kot ksb ksc ksi ksk kso kss kst ktb ktc ktk kto kts ktt o-i ob- obb obc obi obk obo obs obt oc- ocb occ oci ock oco ocs oct oib oic oii oik oio ois oit okb okc oki okk oko oks oo- oob ooc ooi ook ooo oos oot os- osb osc osi osk oso oss ost ot- otb otc oti otk oto ots ott sbb sbc sbi sbk sbo sbs sbt scb scc sci sck sco scs sct sib sic sii sik sio sis sit sk- skb skc ski skk sko sks skt sob soc soi sok soo sos sot ss- ssb ssc ssi ssk sso sss sst stb stc sti stk sto sts stt tbb tbc tbi tbk tbo tbs tbt tcb tcc tci tck tco tcs tct tib tic tii tik tio tis tit tkb tkc tkk tko tks tkt to- tob toc toi tok too tos tot tsb tsc tsi tsk tso tss tst ttb ttc tti ttk tto tts ttt