a-a a-b a-c a-t a-z aaa aab aac aar aat aau aaz ab- aba abb abc abr abt abu abz ac- aca acb acc acr act acu acz ar- ara arb arc arr art aru arz at- ata atb atc atr att atu atz au- aua aub auc aur aut auz az- aza azb azt azu azz b-u baa bab bac bar bat bau baz bba bbb bbc bbr bbt bbu bca bcb bcc bcr bct bcu bcz bra brb brr brt bru brz bta btb btc btr btt btu btz bua bub buc bur but buu buz bza bzr bzu bzz c-- caa cab cac car cat cau caz cba cbb cbc cbr cbt cbu cbz cca ccb ccc ccr cct ccu ccz cra crb crc crr crt cru crz cta ctb ctc ctr ctt ctu ctz cua cub cuc cur cut cuu cuz cz- czc czt ra- raa rab rac rar rat rau raz rba rbb rbc rbr rbt rbu rca rcb rcc rcr rct rcu rra rrb rrc rrr rrt rru rta rtb rtc rtr rtt rtu rtz rua rub ruc rur rut ruu ruz rza rzb taa tab tac tar tat tau taz tba tbb tbc tbr tbt tbu tbz tca tcb tcc tcr tct tcu tra trb trc trr trt tru trz tta ttb ttc ttr ttt ttu tua tub tuc tur tut tuu tuz tza tzu ua- uaa uab uac uar uat uau uaz uba ubb ubc ubr ubt ubu uca ucb ucc ucr uct ucu ur- ura urb urc urr urt uru urz uta utb utc utr utt utu utz uua uuc uur uut uuu uza uzb uzu zaa zab zac zar zat zaz zbb zbc zbr zbt zta ztr zub zuc zur zut zuz zzr zzt zzz