a-a a-b a-c a-t aaa aab aac aaf aak aao aas aat ab- aba abb abc abf abk abo abs abt ac- aca acb acc acf ack aco acs act af- afa afb afc aff afk afo afs aft aka akb akc akk ako aks aoa aob aoc aof aok aoo aos aot as- asa asb asc asf ask aso ass ast at- ata atb atc atf ato ats att baa bab bac baf bak bao bas bat bba bbb bbc bbf bbk bbo bbs bbt bca bcb bcc bcf bck bco bcs bct bfa bfb bfc bff bfo bfs bft bka bkb bkc bkf bkk bko bks bkt boa bob boc bof bok boo bos bot bsa bsb bsc bsf bsk bso bss bst bta btb btc btf btk bto bts btt c-- caa cab cac caf cak cao cas cat cba cbb cbc cbf cbk cbo cbs cbt cca ccb ccc ccf cck cco ccs cct cfa cfb cfc cff cfk cfo cfs cft cka ckb ckc cko cks ckt co- coa cob coc cof cok coo cos cot csa csb csc csf csk cso css cst cta ctb ctc ctf ctk cto cts ctt faa fab fac faf fak fao fas fat fba fbb fbc fbf fbk fbo fbs fbt fca fcb fcc fcf fck fco fcs fct ffa ffc fff ffk ffo ffs fft fka fkb fkc fkf fkk fkt foa fob foc fof fok foo fos fot fsa fsb fsc fsf fsk fso fss fst fta ftb ftc ftf ftk fto fts ftt k-t ka- kaa kab kac kaf kak kao kas kat kba kbb kbc kbf kbk kbo kbs kca kcb kcc kck kcs kct kfa kfc kff kfo kfs kkb kkc kkk kks kkt koa kob koc kof kok koo kos kot ksa ksb ksc ksf ksk kso kss kst kta ktb ktc ktf ktk kto kts ktt oaa oab oac oaf oak oao oas oat ob- oba obb obc obf obk obo obs obt oc- oca ocb occ ocf ock oco ocs oct of- ofa ofb ofc off ofo ofs oft oka okb okc okk oko oks oo- ooa oob ooc oof ook ooo oos oot os- osa osb osc osf osk oso oss ost ot- ota otb otc otf otk oto ots ott saa sab sac saf sak sao sas sat sba sbb sbc sbf sbk sbo sbs sbt sca scb scc scf sck sco scs sct sfa sfb sfc sff sfk sfo sfs sft sk- ska skb skc skf skk sko sks skt soa sob soc sof sok soo sos sot ss- ssa ssb ssc ssf ssk sso sss sst sta stb stc stf stk sto sts stt taa tab tac taf tak tao tas tat tba tbb tbc tbf tbk tbo tbs tbt tca tcb tcc tcf tck tco tcs tct tfa tfb tfc tff tfk tfo tfs tft tka tkb tkc tkk tko tks tkt to- toa tob toc tof tok too tos tot tsa tsb tsc tsf tsk tso tss tst tta ttb ttc ttf ttk tto tts ttt