a-a a-b a-t aaa aab aad aao aat aax ab- aba abb abd abo abt abx ad- ada adb add ado adt adx aoa aob aod aoo aot aox at- ata atb atd ato att atx ax- axa axo axt axx baa bab bad bao bat bax bba bbb bbd bbo bbt bbx bda bdb bdd bdo bdt bdx boa bob bod boo bot box bta btb btd bto btt btx bxb bxd bxo bxx daa dab dad dao dat dax dba dbb dbd dbo dbt dbx dda ddb ddd ddo ddt ddx doa dob dod doo dot dox dta dtb dtd dto dtt dtx dxd dxo dxt dxx oaa oab oad oao oat oax ob- oba obb obd obo obt obx oda odb odd odo odt oo- ooa oob ood ooo oot oox ot- ota otb otd oto ott ox- oxa oxb oxo oxt oxx t-x taa tab tad tao tat tax tba tbb tbd tbo tbt tda tdb tdd tdo tdt tdx to- toa tob tod too tot tox tta ttb ttd tto ttt ttx txt xaa xad xat xbx xda xdb xdt xoa xod xoo xot xox xtx xxo xxx