-ic a-a a-b a-c a-i aaa aab aac aae aai aak aao aax ab- aba abb abc abe abi abk abo abx ac- aca acb acc ace aci ack aco acx aea aeb aec aee aei aek aeo aex ai- aia aib aic aie aii aik aio aix aka akb akc ake aki akk ako aoa aob aoc aoe aoi aok aoo aox ax- axa axe axi axk axo axx baa bab bac bae bai bak bao bax bba bbb bbc bbe bbi bbk bbo bbx bca bcb bcc bce bci bck bco bcx be- bea beb bec bee bei bek beo bex bi- bia bib bic bie bii bik bio bix bka bkb bkc bke bkk bko bkx boa bob boc boe boi bok boo box bxb bxi bxo bxx c-- caa cab cac cae cai cak cao cax cba cbb cbc cbe cbi cbk cbo cbx cca ccb ccc cce cci cck cco ccx ce- cea ceb cec cee cei cek ceo cex ci- cia cib cic cie cii cik cio cix cka ckb ckc cki cko ckx co- coa cob coc coe coi cok coo cox cxc cxi cxk cxo cxx eaa eab eac eae eai eak eao eax eba ebb ebc ebe ebi ebk ebo ebx ec- eca ecb ecc ece eci eck eco ecx eea eeb eec eee eek eeo eex eia eib eic eie eii eik eio eix eka ekb ekc eke eki eko eo- eoa eob eoc eoe eoi eok eoo ex- exa exc exe exi exo exx ia- iaa iab iac iae iai iao iba ibb ibc ibe ibi ibk ibo ibx ica icb icc ice ici ick ico ie- iea iec iee iei iek iex iia iib iic iie iii iio iix ika ikb ikc ike iki ikk iko ikx io- ioa iob ioc ioe ioi ioo ixc ixe ixi ka- kaa kab kac kae kai kak kao kax kba kbb kbc kbe kbi kbk kbo kbx kca kcb kcc kce kci kck kcx ke- kea keb kec kee kei kek keo kex kia kib kic kie kii kik kio kix kkb kkc kke kki kkk koa kob koc koe koi kok koo kxo o-i oaa oab oac oae oai oak oao oax ob- oba obb obc obe obi obk obo obx oc- oca ocb occ oci ock oco ocx oea oeb oec oee oei oeo oex oia oib oic oie oii oik oio oka okb okc oke oki okk oko oo- ooa oob ooc ooi ook ooo oox ox- oxa oxb oxc oxi oxo oxx xaa xac xak xbc xbe xbx xcb xci xcx xee xex xia xic xie xii xio xix xkb xke xoa xoc xoi xok xoo xox xxi xxo xxx