-ic a-a a-b a-c a-i aaa aab aac aaf aai aak aan aao ab- aba abb abc abf abi abk abn abo ac- aca acb acc acf aci ack acn aco af- afa afb afc aff afi afk afn afo ai- aia aib aic aif aii aik ain aio aka akb akc aki akk akn ako an- ana anb anc anf ani ank ann ano aoa aob aoc aof aoi aok aon aoo baa bab bac baf bai bak ban bao bba bbb bbc bbf bbi bbk bbn bbo bca bcb bcc bcf bci bck bcn bco bfa bfb bfc bff bfi bfn bfo bi- bia bib bic bif bii bik bin bio bka bkb bkc bkf bkk bkn bko bna bnb bnc bnf bni bnk bnn bno boa bob boc bof boi bok bon boo c-- caa cab cac caf cai cak can cao cba cbb cbc cbf cbi cbk cbn cbo cca ccb ccc ccf cci cck ccn cco cfa cfb cfc cff cfi cfk cfn cfo ci- cia cib cic cif cii cik cin cio cka ckb ckc cki cko cn- cna cnb cnc cnf cni cnn cno co- coa cob coc cof coi cok con coo faa fab fac faf fai fak fan fao fba fbb fbc fbf fbi fbk fbn fbo fca fcb fcc fcf fci fck fcn fco ffa ffc fff ffi ffk ffn ffo fia fib fic fif fii fik fin fka fkb fkc fkf fki fkk fna fnb fnc fnf fni fnk fnn foa fob foc fof foi fok fon foo i-f ia- iaa iab iac iaf iai ian iao iba ibb ibc ibf ibi ibk ibn ibo ica icb icc icf ici ick icn ico ifa ifb ifc iff ifi ifn ifo iia iib iic iif iii iin iio ika ikb ikc ikf iki ikk iko in- ina inb inc inf ini ink inn ino io- ioa iob ioc iof ioi ion ioo ka- kaa kab kac kaf kai kak kan kao kba kbb kbc kbf kbi kbk kbn kbo kca kcb kcc kci kck kcn kfa kfc kff kfi kfo kia kib kic kif kii kik kin kio kkb kkc kki kkk kkn kn- kna knc knf kni knk knn kno koa kob koc kof koi kok kon koo n-i naa nab nac naf nai nak nan nao nba nbb nbc nbf nbi nbk nbn nbo nca ncb ncc ncf nci nck ncn nco nfa nfb nfc nff nfi nfk nfn nfo nia nib nic nif nii nik nin nio nka nkc nkf nki nkk nkn nko nna nnb nnc nnf nni nnk nnn nno no- noa nob noc nof noi nok non noo o-i oaa oab oac oaf oai oak oan oao ob- oba obb obc obf obi obk obn obo oc- oca ocb occ ocf oci ock ocn oco of- ofa ofb ofc off ofi ofn ofo oia oib oic oif oii oik oin oio oka okb okc oki okk oko on- ona onb onc onf oni onk onn ono oo- ooa oob ooc oof ooi ook oon ooo