a-a a-b a-c aaa aab aac aad aak aao aau ab- aba abb abc abd abk abo abu ac- aca acb acc acd ack aco acu ad- ada adb adc add adk ado adu aka akb akc akd akk ako aku aoa aob aoc aod aok aoo aou au- aua aub auc aud auk auo b-u baa bab bac bad bak bao bau bba bbb bbc bbd bbk bbo bbu bca bcb bcc bcd bck bco bcu bda bdb bdc bdd bdk bdo bdu bka bkb bkc bkk bko boa bob boc bod bok boo bou bua bub buc bud buk buo buu c-- caa cab cac cad cak cao cau cba cbb cbc cbd cbk cbo cbu cca ccb ccc ccd cck cco ccu cda cdb cdc cdd cdk cdo cdu cka ckb ckc ckd cko co- coa cob coc cod cok coo cou cua cub cuc cud cuk cuo cuu daa dab dac dad dak dao dau dba dbb dbc dbd dbk dbo dbu dca dcb dcc dcd dck dco dcu dda ddb ddc ddd ddk ddo ddu dka dkb dkc dkk dko dku doa dob doc dod dok doo dou dua dub duc dud duk duo ka- kaa kab kac kad kak kao kau kba kbb kbc kbd kbk kbo kbu kca kcb kcc kcd kck kcu kda kdb kdc kdk kdo kdu kkb kkc kkk kku koa kob koc kod kok koo kou kub kuc kud kuk kuu oaa oab oac oad oak oao oau ob- oba obb obc obd obk obo obu oc- oca ocb occ ocd ock oco ocu oda odb odc odd odo odu oka okb okc okd okk oko oku oo- ooa oob ooc ood ook ooo ou- oua ouc oud ouk ouo ua- uaa uab uac uad uak uao uau uba ubb ubc ubk ubo ubu uca ucb ucc ucd uck uco ucu uda udb udc udd udk udo udu uka ukb ukc ukk uku uoa uob uoc uod uok uoo uua uuc uuu