a-a a-b a-t aaa aab aad aao aat ab- aba abb abd abo abt ad- ada adb add ado adt aoa aob aod aoo aot at- ata atb atd ato att baa bab bad bao bat bba bbb bbd bbo bbt bda bdb bdd bdo bdt boa bob bod boo bot bta btb btd bto btt daa dab dad dao dat dba dbb dbd dbo dbt dda ddb ddd ddo ddt doa dob dod doo dot dta dtb dtd dto dtt oaa oab oad oao oat ob- oba obb obd obo obt oda odb odd odo odt oo- ooa oob ood ooo oot ot- ota otb otd oto ott taa tab tad tao tat tba tbb tbd tbo tbt tda tdb tdd tdo tdt to- toa tob tod too tot tta ttb ttd tto ttt