-ic bbb bbc bbe bbi bbk bbo bcb bcc bce bci bck bco be- beb bec bee bei bek beo bi- bib bic bie bii bik bio bkb bkc bke bkk bko bob boc boe boi bok boo c-- cbb cbc cbe cbi cbk cbo ccb ccc cce cci cck cco ce- ceb cec cee cei cek ceo ci- cib cic cie cii cik cio ckb ckc cki cko co- cob coc coe coi cok coo ebb ebc ebe ebi ebk ebo ec- ecb ecc ece eci eck eco eeb eec eee eek eeo eib eic eie eii eik eio ekb ekc eke eki eko eo- eob eoc eoe eoi eok eoo ibb ibc ibe ibi ibk ibo icb icc ice ici ick ico ie- iec iee iei iek iib iic iie iii iio ikb ikc ike iki ikk iko io- iob ioc ioe ioi ioo kbb kbc kbe kbi kbk kbo kcb kcc kce kci kck ke- keb kec kee kei kek keo kib kic kie kii kik kio kkb kkc kke kki kkk kob koc koe koi kok koo o-i ob- obb obc obe obi obk obo oc- ocb occ oci ock oco oeb oec oee oei oeo oib oic oie oii oik oio okb okc oke oki okk oko oo- oob ooc ooi ook ooo