a-a a-b a-t aaa aab aaf aak aan aao aas aat ab- aba abb abf abk abn abo abs abt af- afa afb aff afk afn afo afs aft aka akb akk akn ako aks an- ana anb anf ank ann ano ans ant aoa aob aof aok aon aoo aos aot as- asa asb asf ask asn aso ass ast at- ata atb atf atn ato ats att baa bab baf bak ban bao bas bat bba bbb bbf bbk bbn bbo bbs bbt bfa bfb bff bfn bfo bfs bft bka bkb bkf bkk bkn bko bks bkt bna bnb bnf bnk bnn bno bns bnt boa bob bof bok bon boo bos bot bsa bsb bsf bsk bsn bso bss bst bta btb btf btk btn bto bts btt faa fab faf fak fan fao fas fat fba fbb fbf fbk fbn fbo fbs fbt ffa fff ffk ffn ffo ffs fft fka fkb fkf fkk fkt fna fnb fnf fnk fnn fns fnt foa fob fof fok fon foo fos fot fsa fsb fsf fsk fsn fso fss fst fta ftb ftf ftk ftn fto fts ftt k-t ka- kaa kab kaf kak kan kao kas kat kba kbb kbf kbk kbn kbo kbs kfa kff kfo kfs kkb kkk kkn kks kkt kn- kna knf knk knn kno knt koa kob kof kok kon koo kos kot ksa ksb ksf ksk ksn kso kss kst kta ktb ktf ktk ktn kto kts ktt naa nab naf nak nan nao nas nat nba nbb nbf nbk nbn nbo nbs nbt nfa nfb nff nfk nfn nfo nfs nft nka nkf nkk nkn nko nks nkt nna nnb nnf nnk nnn nno nns nnt no- noa nob nof nok non noo nos not nsa nsb nsf nsk nsn nso nss nst nta ntb ntf ntk ntn nto nts ntt oaa oab oaf oak oan oao oas oat ob- oba obb obf obk obn obo obs obt of- ofa ofb off ofn ofo ofs oft oka okb okk oko oks on- ona onb onf onk onn ono ons ont oo- ooa oob oof ook oon ooo oos oot os- osa osb osf osk osn oso oss ost ot- ota otb otf otk otn oto ots ott saa sab saf sak san sao sas sat sba sbb sbf sbk sbn sbo sbs sbt sfa sfb sff sfk sfn sfo sfs sft sk- ska skb skf skk sko sks skt sna snb snf snk snn sno sns snt soa sob sof sok son soo sos sot ss- ssa ssb ssf ssk ssn sso sss sst sta stb stf stk stn sto sts stt taa tab taf tak tan tao tas tat tba tbb tbf tbk tbn tbo tbs tbt tfa tfb tff tfk tfn tfo tfs tft tka tkb tkk tko tks tkt tna tnb tnf tnk tnn tno tns tnt to- toa tob tof tok ton too tos tot tsa tsb tsf tsk tsn tso tss tst tta ttb ttf ttk ttn tto tts ttt