a-a a-b a-c a-t aaa aab aac aak aao aar aat ab- aba abb abc abk abo abr abt ac- aca acb acc ack aco acr act aka akb akc akk ako akr aoa aob aoc aok aoo aor aot ar- ara arb arc ark aro arr art at- ata atb atc ato atr att baa bab bac bak bao bar bat bba bbb bbc bbk bbo bbr bbt bca bcb bcc bck bco bcr bct bka bkb bkc bkk bko bkr bkt boa bob boc bok boo bor bot bra brb brk bro brr brt bta btb btc btk bto btr btt c-- caa cab cac cak cao car cat cba cbb cbc cbk cbo cbr cbt cca ccb ccc cck cco ccr cct cka ckb ckc cko ckt co- coa cob coc cok coo cor cot cra crb crc crk cro crr crt cta ctb ctc ctk cto ctr ctt k-t ka- kaa kab kac kak kao kar kat kba kbb kbc kbk kbo kbr kca kcb kcc kck kcr kct kkb kkc kkk kkr kkt koa kob koc kok koo kor kot kra krc krk kro krr krt kta ktb ktc ktk kto ktr ktt oaa oab oac oak oao oar oat ob- oba obb obc obk obo obr obt oc- oca ocb occ ock oco ocr oct oka okb okc okk oko okr oo- ooa oob ooc ook ooo oor oot or- ora orb orc ork oro orr ort ot- ota otb otc otk oto otr ott ra- raa rab rac rak rao rar rat rba rbb rbc rbk rbo rbr rbt rca rcb rcc rco rcr rct rkb rkc rkk rko rkt roa rob roc rok roo ror rot rra rrb rrc rrk rrr rrt rta rtb rtc rtk rto rtr rtt taa tab tac tak tao tar tat tba tbb tbc tbk tbo tbr tbt tca tcb tcc tck tco tcr tct tka tkb tkc tkk tko tkr tkt to- toa tob toc tok too tor tot tra trb trc trk tro trr trt tta ttb ttc ttk tto ttr ttt