a-a a-b a-q a-t aaa aab aao aaq aar aat ab- aba abb abo abq abr abt aoa aob aoo aor aot aqa aqo aqr aqt ar- ara arb aro arq arr art at- ata atb ato atr att baa bab bao baq bar bat bba bbb bbo bbq bbr bbt boa bob boo boq bor bot bqt bra brb bro brq brr brt bta btb bto btq btr btt oaa oab oao oaq oar oat ob- oba obb obo obr obt oo- ooa oob ooo oor oot oqb oqo or- ora orb oro orr ort ot- ota otb oto otr ott qaa qar qat qba qbq qoo qor qqq qra qrb qrt qta qto qtq qtr ra- raa rab rao raq rar rat rba rbb rbo rbr rbt roa rob roo ror rot rra rrb rrq rrr rrt rta rtb rto rtq rtr rtt taa tab tao taq tar tat tba tbb tbo tbr tbt to- toa tob too toq tor tot tqo tra trb tro trq trr trt tta ttb tto ttr ttt