a-a a-b a-c a-t aaa aab aac aaf aak aas aat ab- aba abb abc abf abk abs abt ac- aca acb acc acf ack acs act af- afa afb afc aff afk afs aft aka akb akc akk aks as- asa asb asc asf ask ass ast at- ata atb atc atf ats att baa bab bac baf bak bas bat bba bbb bbc bbf bbk bbs bbt bca bcb bcc bcf bck bcs bct bfa bfb bfc bff bfs bft bka bkb bkc bkf bkk bks bkt bsa bsb bsc bsf bsk bss bst bta btb btc btf btk bts btt c-- caa cab cac caf cak cas cat cba cbb cbc cbf cbk cbs cbt cca ccb ccc ccf cck ccs cct cfa cfb cfc cff cfk cfs cft cka ckb ckc cks ckt csa csb csc csf csk css cst cta ctb ctc ctf ctk cts ctt faa fab fac faf fak fas fat fba fbb fbc fbf fbk fbs fbt fca fcb fcc fcf fck fcs fct ffa ffc fff ffk ffs fft fka fkb fkc fkf fkk fkt fsa fsb fsc fsf fsk fss fst fta ftb ftc ftf ftk fts ftt k-t ka- kaa kab kac kaf kak kas kat kba kbb kbc kbf kbk kbs kca kcb kcc kck kcs kct kfa kfc kff kfs kkb kkc kkk kks kkt ksa ksb ksc ksf ksk kss kst kta ktb ktc ktf ktk kts ktt saa sab sac saf sak sas sat sba sbb sbc sbf sbk sbs sbt sca scb scc scf sck scs sct sfa sfb sfc sff sfk sfs sft sk- ska skb skc skf skk sks skt ss- ssa ssb ssc ssf ssk sss sst sta stb stc stf stk sts stt taa tab tac taf tak tas tat tba tbb tbc tbf tbk tbs tbt tca tcb tcc tcf tck tcs tct tfa tfb tfc tff tfk tfs tft tka tkb tkc tkk tks tkt tsa tsb tsc tsf tsk tss tst tta ttb ttc ttf ttk tts ttt