a-a a-b a-t a-z aaa aab aar aat aau aaz ab- aba abb abr abt abu abz ar- ara arb arr art aru arz at- ata atb atr att atu atz au- aua aub aur aut auz az- aza azb azt azu azz b-u baa bab bar bat bau baz bba bbb bbr bbt bbu bra brb brr brt bru brz bta btb btr btt btu btz bua bub bur but buu buz bza bzr bzu bzz ra- raa rab rar rat rau raz rba rbb rbr rbt rbu rra rrb rrr rrt rru rta rtb rtr rtt rtu rtz rua rub rur rut ruu ruz rza rzb taa tab tar tat tau taz tba tbb tbr tbt tbu tbz tra trb trr trt tru trz tta ttb ttr ttt ttu tua tub tur tut tuu tuz tza tzu ua- uaa uab uar uat uau uaz uba ubb ubr ubt ubu ur- ura urb urr urt uru urz uta utb utr utt utu utz uua uur uut uuu uza uzb uzu zaa zab zar zat zaz zbb zbr zbt zta ztr zub zur zut zuz zzr zzt zzz