a-a a-b a-q a-t aaa aab aao aaq aat ab- aba abb abo abq abt aoa aob aoo aot aqa aqo aqt at- ata atb ato att baa bab bao baq bat bba bbb bbo bbq bbt boa bob boo boq bot bqt bta btb bto btq btt oaa oab oao oaq oat ob- oba obb obo obt oo- ooa oob ooo oot oqb oqo ot- ota otb oto ott qaa qat qba qbq qoo qqq qta qto qtq taa tab tao taq tat tba tbb tbo tbt to- toa tob too toq tot tqo tta ttb tto ttt