-ic a-a a-b a-c a-i aaa aab aac aae aaf aai aak aao ab- aba abb abc abe abf abi abk abo ac- aca acb acc ace acf aci ack aco aea aeb aec aee aef aei aek aeo af- afa afb afc afe aff afi afk afo ai- aia aib aic aie aif aii aik aio aka akb akc ake aki akk ako aoa aob aoc aoe aof aoi aok aoo baa bab bac bae baf bai bak bao bba bbb bbc bbe bbf bbi bbk bbo bca bcb bcc bce bcf bci bck bco be- bea beb bec bee bef bei bek beo bfa bfb bfc bfe bff bfi bfo bi- bia bib bic bie bif bii bik bio bka bkb bkc bke bkf bkk bko boa bob boc boe bof boi bok boo c-- caa cab cac cae caf cai cak cao cba cbb cbc cbe cbf cbi cbk cbo cca ccb ccc cce ccf cci cck cco ce- cea ceb cec cee cef cei cek ceo cfa cfb cfc cfe cff cfi cfk cfo ci- cia cib cic cie cif cii cik cio cka ckb ckc cki cko co- coa cob coc coe cof coi cok coo eaa eab eac eae eaf eai eak eao eba ebb ebc ebe ebf ebi ebk ebo ec- eca ecb ecc ece ecf eci eck eco eea eeb eec eee eef eek eeo ef- efa efb efc efe eff efi efo eia eib eic eie eif eii eik eio eka ekb ekc eke ekf eki eko eo- eoa eob eoc eoe eof eoi eok eoo faa fab fac fae faf fai fak fao fba fbb fbc fbe fbf fbi fbk fbo fca fcb fcc fce fcf fci fck fco fea feb fec fee fef fei fek feo ffa ffc ffe fff ffi ffk ffo fia fib fic fie fif fii fik fka fkb fkc fkf fki fkk foa fob foc foe fof foi fok foo i-f ia- iaa iab iac iae iaf iai iao iba ibb ibc ibe ibf ibi ibk ibo ica icb icc ice icf ici ick ico ie- iea iec iee ief iei iek ifa ifb ifc ife iff ifi ifo iia iib iic iie iif iii iio ika ikb ikc ike ikf iki ikk iko io- ioa iob ioc ioe iof ioi ioo ka- kaa kab kac kae kaf kai kak kao kba kbb kbc kbe kbf kbi kbk kbo kca kcb kcc kce kci kck ke- kea keb kec kee kef kei kek keo kfa kfc kff kfi kfo kia kib kic kie kif kii kik kio kkb kkc kke kki kkk koa kob koc koe kof koi kok koo o-i oaa oab oac oae oaf oai oak oao ob- oba obb obc obe obf obi obk obo oc- oca ocb occ ocf oci ock oco oea oeb oec oee oef oei oeo of- ofa ofb ofc ofe off ofi ofo oia oib oic oie oif oii oik oio oka okb okc oke oki okk oko oo- ooa oob ooc oof ooi ook ooo