a-a a-b a-t aaa aab aae aak aao aas aat ab- aba abb abe abk abo abs abt aea aeb aee aek aeo aes aet aka akb ake akk ako aks aoa aob aoe aok aoo aos aot as- asa asb ase ask aso ass ast at- ata atb ate ato ats att baa bab bae bak bao bas bat bba bbb bbe bbk bbo bbs bbt be- bea beb bee bek beo bes bet bka bkb bke bkk bko bks bkt boa bob boe bok boo bos bot bsa bsb bse bsk bso bss bst bta btb bte btk bto bts btt eaa eab eae eak eao eas eat eba ebb ebe ebk ebo ebs ebt eea eeb eee eek eeo ees eet eka ekb eke eko eks ekt eo- eoa eob eoe eok eoo eos eot es- esa esb ese esk eso ess est eta etb ete etk eto ets ett k-t ka- kaa kab kae kak kao kas kat kba kbb kbe kbk kbo kbs ke- kea keb kee kek keo kes ket kkb kke kkk kks kkt koa kob koe kok koo kos kot ksa ksb kse ksk kso kss kst kta ktb kte ktk kto kts ktt oaa oab oae oak oao oas oat ob- oba obb obe obk obo obs obt oea oeb oee oeo oes oet oka okb oke okk oko oks oo- ooa oob ook ooo oos oot os- osa osb ose osk oso oss ost ot- ota otb ote otk oto ots ott saa sab sae sak sao sas sat sba sbb sbe sbk sbo sbs sbt se- sea seb see sek seo ses set sk- ska skb ske skk sko sks skt soa sob soe sok soo sos sot ss- ssa ssb sse ssk sso sss sst sta stb ste stk sto sts stt taa tab tae tak tao tas tat tba tbb tbe tbk tbo tbs tbt te- tea teb tee tek teo tes tet tka tkb tke tkk tko tks tkt to- toa tob toe tok too tos tot tsa tsb tse tsk tso tss tst tta ttb tte ttk tto tts ttt