a-a a-b a-c aaa aab aac aak aan aao aar aas aau ab- aba abb abc abk abn abo abr abs abu ac- aca acb acc ack acn aco acr acs acu aka akb akc akk akn ako akr aks aku an- ana anb anc ank ann ano anr ans anu aoa aob aoc aok aon aoo aor aos aou ar- ara arb arc ark arn aro arr ars aru as- asa asb asc ask asn aso asr ass asu au- aua aub auc auk aun auo aur aus b-u baa bab bac bak ban bao bar bas bau bba bbb bbc bbk bbn bbo bbr bbs bbu bca bcb bcc bck bcn bco bcr bcs bcu bka bkb bkc bkk bkn bko bkr bks bna bnb bnc bnk bnn bno bnr bns bnu boa bob boc bok bon boo bor bos bou bra brb brk brn bro brr brs bru bsa bsb bsc bsk bsn bso bsr bss bsu bua bub buc buk bun buo bur bus buu c-- caa cab cac cak can cao car cas cau cba cbb cbc cbk cbn cbo cbr cbs cbu cca ccb ccc cck ccn cco ccr ccs ccu cka ckb ckc cko cks cn- cna cnb cnc cnn cno cnr cns cnu co- coa cob coc cok con coo cor cos cou cra crb crc crk crn cro crr crs cru csa csb csc csk csn cso csr css csu cua cub cuc cuk cun cuo cur cus cuu ka- kaa kab kac kak kan kao kar kas kau kba kbb kbc kbk kbn kbo kbr kbs kbu kca kcb kcc kck kcn kcr kcs kcu kkb kkc kkk kkn kkr kks kku kn- kna knc knk knn kno knr knu koa kob koc kok kon koo kor kos kou kra krc krk krn kro krr krs kru ksa ksb ksc ksk ksn kso ksr kss ksu kub kuc kuk kun kur kus kuu naa nab nac nak nan nao nar nas nau nba nbb nbc nbk nbn nbo nbr nbs nbu nca ncb ncc nck ncn nco ncr ncs ncu nka nkc nkk nkn nko nkr nks nku nna nnb nnc nnk nnn nno nns nnu no- noa nob noc nok non noo nor nos nou nra nrb nrc nrk nrn nro nrr nrs nru nsa nsb nsc nsk nsn nso nsr nss nsu nua nub nuc nuk nun nuo nur nus nuu oaa oab oac oak oan oao oar oas oau ob- oba obb obc obk obn obo obr obs obu oc- oca ocb occ ock ocn oco ocr ocs ocu oka okb okc okk oko okr oks oku on- ona onb onc onk onn ono onr ons onu oo- ooa oob ooc ook oon ooo oor oos or- ora orb orc ork orn oro orr ors oru os- osa osb osc osk osn oso osr oss osu ou- oua ouc ouk oun ouo our ous ra- raa rab rac rak ran rao rar ras rau rba rbb rbc rbk rbn rbo rbr rbs rbu rca rcb rcc rcn rco rcr rcs rcu rkb rkc rkk rko rks rku rna rnb rnc rnn rno rnr rns rnu roa rob roc rok ron roo ror ros rou rra rrb rrc rrk rrn rrr rrs rru rsa rsb rsc rsk rsn rso rsr rss rsu rua rub ruc ruk run ruo rur rus ruu saa sab sac sak san sao sar sas sau sba sbb sbc sbk sbn sbo sbr sbs sbu sca scb scc sck scn sco scr scs scu sk- ska skb skc skk sko skr sks sku sna snb snc snk snn sno snr sns snu soa sob soc sok son soo sor sos sou sr- sra srb src srk srn sro srr srs ss- ssa ssb ssc ssk ssn sso ssr sss ssu sua sub suc suk sun suo sur sus suu ua- uaa uab uac uak uan uao uar uas uau uba ubb ubc ubk ubn ubo ubr ubs ubu uca ucb ucc uck ucn uco ucr ucs ucu uka ukb ukc ukk ukn ukr uku un- una unb unc unk unn uno unr uns unu uoa uob uoc uok uon uoo uor uos ur- ura urb urc urk urn uro urr urs uru usa usb usc usk usn uso usr uss usu uua uuc uun uur uus uuu