-ic bbb bbc bbi bbk bbo bbs bcb bcc bci bck bco bcs bi- bib bic bii bik bio bis bkb bkc bkk bko bks bob boc boi bok boo bos bsb bsc bsi bsk bso bss c-- cbb cbc cbi cbk cbo cbs ccb ccc cci cck cco ccs ci- cib cic cii cik cio cis ckb ckc cki cko cks co- cob coc coi cok coo cos csb csc csi csk cso css ibb ibc ibi ibk ibo ibs icb icc ici ick ico ics iib iic iii iio iis ikb ikc iki ikk iko iks io- iob ioc ioi ioo ios is- isb isc isi isk iso iss kbb kbc kbi kbk kbo kbs kcb kcc kci kck kcs kib kic kii kik kio kis kkb kkc kki kkk kks kob koc koi kok koo kos ksb ksc ksi ksk kso kss o-i ob- obb obc obi obk obo obs oc- ocb occ oci ock oco ocs oib oic oii oik oio ois okb okc oki okk oko oks oo- oob ooc ooi ook ooo oos os- osb osc osi osk oso oss sbb sbc sbi sbk sbo sbs scb scc sci sck sco scs sib sic sii sik sio sis sk- skb skc ski skk sko sks sob soc soi sok soo sos ss- ssb ssc ssi ssk sso sss