a-a a-b a-c aaa aab aac aaf aak aan aar aau ab- aba abb abc abf abk abn abr abu ac- aca acb acc acf ack acn acr acu af- afa afb afc aff afk afn afr afu aka akb akc akk akn akr aku an- ana anb anc anf ank ann anr anu ar- ara arb arc arf ark arn arr aru au- aua aub auc auf auk aun aur b-u baa bab bac baf bak ban bar bau bba bbb bbc bbf bbk bbn bbr bbu bca bcb bcc bcf bck bcn bcr bcu bfa bfb bfc bff bfn bfr bfu bka bkb bkc bkf bkk bkn bkr bna bnb bnc bnf bnk bnn bnr bnu bra brb brf brk brn brr bru bua bub buc buf buk bun bur buu c-- caa cab cac caf cak can car cau cba cbb cbc cbf cbk cbn cbr cbu cca ccb ccc ccf cck ccn ccr ccu cfa cfb cfc cff cfk cfn cfr cfu cka ckb ckc cn- cna cnb cnc cnf cnn cnr cnu cra crb crc crf crk crn crr cru cua cub cuc cuf cuk cun cur cuu faa fab fac faf fak fan far fau fba fbb fbc fbf fbk fbn fbr fbu fca fcb fcc fcf fck fcn fcr fcu ffa ffc fff ffk ffn ffr ffu fka fkb fkc fkf fkk fna fnb fnc fnf fnk fnn fnr fnu fra frb frc frf frk frn frr fru fua fub fuf fuk fun fur fuu ka- kaa kab kac kaf kak kan kar kau kba kbb kbc kbf kbk kbn kbr kbu kca kcb kcc kck kcn kcr kcu kfa kfc kff kfu kkb kkc kkk kkn kkr kku kn- kna knc knf knk knn knr knu kra krc krf krk krn krr kru kub kuc kuk kun kur kuu naa nab nac naf nak nan nar nau nba nbb nbc nbf nbk nbn nbr nbu nca ncb ncc ncf nck ncn ncr ncu nfa nfb nfc nff nfk nfn nfr nfu nka nkc nkf nkk nkn nkr nku nna nnb nnc nnf nnk nnn nnu nra nrb nrc nrf nrk nrn nrr nru nua nub nuc nuk nun nur nuu ra- raa rab rac raf rak ran rar rau rba rbb rbc rbf rbk rbn rbr rbu rca rcb rcc rcf rcn rcr rcu rfa rfb rfc rff rfk rfn rfr rfu rkb rkc rkf rkk rku rna rnb rnc rnn rnr rnu rra rrb rrc rrf rrk rrn rrr rru rua rub ruc ruf ruk run rur ruu ua- uaa uab uac uaf uak uan uar uau uba ubb ubc ubf ubk ubn ubr ubu uca ucb ucc ucf uck ucn ucr ucu ufa ufc uff ufn ufr ufu uka ukb ukc ukf ukk ukn ukr uku un- una unb unc unf unk unn unr unu ur- ura urb urc urf urk urn urr uru uua uuc uun uur uuu