-ic a-a a-b a-c a-i aaa aab aac aae aai aak aao aas ab- aba abb abc abe abi abk abo abs ac- aca acb acc ace aci ack aco acs aea aeb aec aee aei aek aeo aes ai- aia aib aic aie aii aik aio ais aka akb akc ake aki akk ako aks aoa aob aoc aoe aoi aok aoo aos as- asa asb asc ase asi ask aso ass baa bab bac bae bai bak bao bas bba bbb bbc bbe bbi bbk bbo bbs bca bcb bcc bce bci bck bco bcs be- bea beb bec bee bei bek beo bes bi- bia bib bic bie bii bik bio bis bka bkb bkc bke bkk bko bks boa bob boc boe boi bok boo bos bsa bsb bsc bse bsi bsk bso bss c-- caa cab cac cae cai cak cao cas cba cbb cbc cbe cbi cbk cbo cbs cca ccb ccc cce cci cck cco ccs ce- cea ceb cec cee cei cek ceo ces ci- cia cib cic cie cii cik cio cis cka ckb ckc cki cko cks co- coa cob coc coe coi cok coo cos csa csb csc cse csi csk cso css eaa eab eac eae eai eak eao eas eba ebb ebc ebe ebi ebk ebo ebs ec- eca ecb ecc ece eci eck eco ecs eea eeb eec eee eek eeo ees eia eib eic eie eii eik eio eis eka ekb ekc eke eki eko eks eo- eoa eob eoc eoe eoi eok eoo eos es- esa esb esc ese esi esk eso ess ia- iaa iab iac iae iai iao ias iba ibb ibc ibe ibi ibk ibo ibs ica icb icc ice ici ick ico ics ie- iea iec iee iei iek ies iia iib iic iie iii iio iis ika ikb ikc ike iki ikk iko iks io- ioa iob ioc ioe ioi ioo ios is- isa isb isc ise isi isk iso iss ka- kaa kab kac kae kai kak kao kas kba kbb kbc kbe kbi kbk kbo kbs kca kcb kcc kce kci kck kcs ke- kea keb kec kee kei kek keo kes kia kib kic kie kii kik kio kis kkb kkc kke kki kkk kks koa kob koc koe koi kok koo kos ksa ksb ksc kse ksi ksk kso kss o-i oaa oab oac oae oai oak oao oas ob- oba obb obc obe obi obk obo obs oc- oca ocb occ oci ock oco ocs oea oeb oec oee oei oeo oes oia oib oic oie oii oik oio ois oka okb okc oke oki okk oko oks oo- ooa oob ooc ooi ook ooo oos os- osa osb osc ose osi osk oso oss saa sab sac sae sai sak sao sas sba sbb sbc sbe sbi sbk sbo sbs sca scb scc sce sci sck sco scs se- sea seb sec see sei sek seo ses sia sib sic sie sii sik sio sis sk- ska skb skc ske ski skk sko sks soa sob soc soe soi sok soo sos ss- ssa ssb ssc sse ssi ssk sso sss