a-a a-b a-c aaa aab aac aad aak aao aar aau ab- aba abb abc abd abk abo abr abu ac- aca acb acc acd ack aco acr acu ad- ada adb adc add adk ado adr adu aka akb akc akd akk ako akr aku aoa aob aoc aod aok aoo aor aou ar- ara arb arc ard ark aro arr aru au- aua aub auc aud auk auo aur b-u baa bab bac bad bak bao bar bau bba bbb bbc bbd bbk bbo bbr bbu bca bcb bcc bcd bck bco bcr bcu bda bdb bdc bdd bdk bdo bdr bdu bka bkb bkc bkk bko bkr boa bob boc bod bok boo bor bou bra brb brd brk bro brr bru bua bub buc bud buk buo bur buu c-- caa cab cac cad cak cao car cau cba cbb cbc cbd cbk cbo cbr cbu cca ccb ccc ccd cck cco ccr ccu cda cdb cdc cdd cdk cdo cdr cdu cka ckb ckc ckd cko co- coa cob coc cod cok coo cor cou cra crb crc crd crk cro crr cru cua cub cuc cud cuk cuo cur cuu daa dab dac dad dak dao dar dau dba dbb dbc dbd dbk dbo dbr dbu dca dcb dcc dcd dck dco dcr dcu dda ddb ddc ddd ddk ddo ddr ddu dka dkb dkc dkk dko dkr dku doa dob doc dod dok doo dor dou dra drb drc drd drk dro drr dru dua dub duc dud duk duo dur ka- kaa kab kac kad kak kao kar kau kba kbb kbc kbd kbk kbo kbr kbu kca kcb kcc kcd kck kcr kcu kda kdb kdc kdk kdo kdr kdu kkb kkc kkk kkr kku koa kob koc kod kok koo kor kou kra krc krd krk kro krr kru kub kuc kud kuk kur kuu oaa oab oac oad oak oao oar oau ob- oba obb obc obd obk obo obr obu oc- oca ocb occ ocd ock oco ocr ocu oda odb odc odd odo odr odu oka okb okc okd okk oko okr oku oo- ooa oob ooc ood ook ooo oor or- ora orb orc ord ork oro orr oru ou- oua ouc oud ouk ouo our ra- raa rab rac rad rak rao rar rau rba rbb rbc rbd rbk rbo rbr rbu rca rcb rcc rcd rco rcr rcu rda rdb rdc rdd rdo rdr rdu rkb rkc rkk rko rku roa rob roc rod rok roo ror rou rra rrb rrc rrd rrk rrr rru rua rub ruc rud ruk ruo rur ruu ua- uaa uab uac uad uak uao uar uau uba ubb ubc ubk ubo ubr ubu uca ucb ucc ucd uck uco ucr ucu uda udb udc udd udk udo udr udu uka ukb ukc ukk ukr uku uoa uob uoc uod uok uoo uor ur- ura urb urc urd urk uro urr uru uua uuc uur uuu