a-a a-b a-t aaa aab aad aaf aao aat aay ab- aba abb abd abf abo abt aby ad- ada adb add adf ado adt ady af- afa afb afd aff afo aft afy aoa aob aod aof aoo aot at- ata atb atd atf ato att ay- aya ayd ayf ayo ayt baa bab bad baf bao bat bay bba bbb bbd bbf bbo bbt bby bda bdb bdd bdf bdo bdt bdy bfa bfb bfd bff bfo bft bfy boa bob bod bof boo bot boy bta btb btd btf bto btt bty by- bya byd byf byo byt daa dab dad daf dao dat day dba dbb dbd dbf dbo dbt dby dda ddb ddd ddf ddo ddt ddy dfa dfb dfd dff dfo dft doa dob dod dof doo dot doy dta dtb dtd dtf dto dtt dty dy- dya dyb dyd dyo dyy faa fab fad faf fao fat fay fba fbb fbd fbf fbo fbt fda fdb fdd fdf fdo fdt ffa ffd fff ffo fft ffy foa fob fof foo fot foy fta ftb ftd ftf fto ftt fty fy- fya fyb fyo oaa oab oad oaf oao oat ob- oba obb obd obf obo obt oby oda odb odd odf odo odt of- ofa ofb ofd off ofo oft oo- ooa oob ood oof ooo oot ot- ota otb otd otf oto ott oya oyd oyo taa tab tad taf tao tat tay tba tbb tbd tbf tbo tbt tda tdb tdd tdf tdo tdt tdy tfa tfb tfd tff tfo tft to- toa tob tod tof too tot toy tta ttb ttd ttf tto ttt tty tya tyd tyf tyo tyt yaa yab yad yaf yao yat yay ybf yby yda ydo ydt ydy yfa yfd yff yft yob yod yof yoo yot yoy yta ytd ytf yto ytt yyb yyf yyt yyy