a-a a-b a-t a-z aaa aab aao aar aat aaz ab- aba abb abo abr abt abz aoa aob aoo aor aot ar- ara arb aro arr art arz at- ata atb ato atr att atz az- aza azb azo azt azz baa bab bao bar bat baz bba bbb bbo bbr bbt boa bob boo bor bot boz bra brb bro brr brt brz bta btb bto btr btt btz bza bzo bzr bzz oaa oab oao oar oat ob- oba obb obo obr obt oo- ooa oob ooo oor oot or- ora orb oro orr ort orz ot- ota otb oto otr ott otz oza ozo ozt ozz ra- raa rab rao rar rat raz rba rbb rbo rbr rbt roa rob roo ror rot roz rra rrb rrr rrt rta rtb rto rtr rtt rtz rza rzb rzo taa tab tao tar tat taz tba tbb tbo tbr tbt tbz to- toa tob too tor tot toz tra trb tro trr trt trz tta ttb tto ttr ttt tza zaa zab zao zar zat zaz zbb zbr zbt zo- zoa zob zoo zor zot zro zta ztr zzr zzt zzz