a-a a-b a-c a-t aaa aab aac aak aao aat aay ab- aba abb abc abk abo abt aby ac- aca acb acc ack aco act acy aka akb akc akk ako aoa aob aoc aok aoo aot at- ata atb atc ato att ay- aya ayc ayk ayo ayt baa bab bac bak bao bat bay bba bbb bbc bbk bbo bbt bby bca bcb bcc bck bco bct bcy bka bkb bkc bkk bko bkt boa bob boc bok boo bot boy bta btb btc btk bto btt bty by- bya byc byk byo byt c-- caa cab cac cak cao cat cay cba cbb cbc cbk cbo cbt cby cca ccb ccc cck cco cct cka ckb ckc cko ckt cky co- coa cob coc cok coo cot coy cta ctb ctc ctk cto ctt cty cya cyb cyc cyk cyo cyt k-t ka- kaa kab kac kak kao kat kay kba kbb kbc kbk kbo kca kcb kcc kck kct kkb kkc kkk kkt kky koa kob koc kok koo kot koy kta ktb ktc ktk kto ktt kya kyc kyo kyt oaa oab oac oak oao oat ob- oba obb obc obk obo obt oby oc- oca ocb occ ock oco oct oka okb okc okk oko oo- ooa oob ooc ook ooo oot ot- ota otb otc otk oto ott oya oyo taa tab tac tak tao tat tay tba tbb tbc tbk tbo tbt tca tcb tcc tck tco tct tka tkb tkc tkk tko tkt tky to- toa tob toc tok too tot toy tta ttb ttc ttk tto ttt tty tya tyc tyo tyt yaa yab yac yak yao yat yay ybc yby yca ycc yco ycy yka ykk yob yoc yok yoo yot yoy yta ytc ytk yto ytt yyb yyc yyt yyy