a-a a-b a-c a-t aaa aab aac aae aak aao aas aat ab- aba abb abc abe abk abo abs abt ac- aca acb acc ace ack aco acs act aea aeb aec aee aek aeo aes aet aka akb akc ake akk ako aks aoa aob aoc aoe aok aoo aos aot as- asa asb asc ase ask aso ass ast at- ata atb atc ate ato ats att baa bab bac bae bak bao bas bat bba bbb bbc bbe bbk bbo bbs bbt bca bcb bcc bce bck bco bcs bct be- bea beb bec bee bek beo bes bet bka bkb bkc bke bkk bko bks bkt boa bob boc boe bok boo bos bot bsa bsb bsc bse bsk bso bss bst bta btb btc bte btk bto bts btt c-- caa cab cac cae cak cao cas cat cba cbb cbc cbe cbk cbo cbs cbt cca ccb ccc cce cck cco ccs cct ce- cea ceb cec cee cek ceo ces cet cka ckb ckc cko cks ckt co- coa cob coc coe cok coo cos cot csa csb csc cse csk cso css cst cta ctb ctc cte ctk cto cts ctt eaa eab eac eae eak eao eas eat eba ebb ebc ebe ebk ebo ebs ebt ec- eca ecb ecc ece eck eco ecs ect eea eeb eec eee eek eeo ees eet eka ekb ekc eke eko eks ekt eo- eoa eob eoc eoe eok eoo eos eot es- esa esb esc ese esk eso ess est eta etb etc ete etk eto ets ett k-t ka- kaa kab kac kae kak kao kas kat kba kbb kbc kbe kbk kbo kbs kca kcb kcc kce kck kcs kct ke- kea keb kec kee kek keo kes ket kkb kkc kke kkk kks kkt koa kob koc koe kok koo kos kot ksa ksb ksc kse ksk kso kss kst kta ktb ktc kte ktk kto kts ktt oaa oab oac oae oak oao oas oat ob- oba obb obc obe obk obo obs obt oc- oca ocb occ ock oco ocs oct oea oeb oec oee oeo oes oet oka okb okc oke okk oko oks oo- ooa oob ooc ook ooo oos oot os- osa osb osc ose osk oso oss ost ot- ota otb otc ote otk oto ots ott saa sab sac sae sak sao sas sat sba sbb sbc sbe sbk sbo sbs sbt sca scb scc sce sck sco scs sct se- sea seb sec see sek seo ses set sk- ska skb skc ske skk sko sks skt soa sob soc soe sok soo sos sot ss- ssa ssb ssc sse ssk sso sss sst sta stb stc ste stk sto sts stt taa tab tac tae tak tao tas tat tba tbb tbc tbe tbk tbo tbs tbt tca tcb tcc tce tck tco tcs tct te- tea teb tec tee tek teo tes tet tka tkb tkc tke tkk tko tks tkt to- toa tob toc toe tok too tos tot tsa tsb tsc tse tsk tso tss tst tta ttb ttc tte ttk tto tts ttt