a-a a-b a-i a-t aaa aab aai aar aat aax ab- aba abb abi abr abt abx ai- aia aib aii air ait aix ar- ara arb ari arr art arx at- ata atb ati atr att atx ax- axa axi axr axt axx baa bab bai bar bat bax bba bbb bbi bbr bbt bbx bi- bia bib bii bir bit bix bra brb bri brr brt brx bta btb bti btr btt btx bxb bxi bxx ia- iaa iab iai iar iat iba ibb ibi ibr ibt ibx iia iib iii iir iit iix ir- ira irb iri irr irt irx ita itb iti itt itx ixi ra- raa rab rai rar rat rax rba rbb rbi rbr rbt rbx ria rib rii rir rit rix rra rrb rri rrr rrt rta rtb rti rtr rtt rtx rxr t-x taa tab tai tar tat tax tba tbb tbi tbr tbt tia tib tii tir tit tix tra trb tri trr trt trx tta ttb tti ttr ttt ttx txi txt xaa xar xat xbr xbx xia xii xit xix xrt xrx xti xtr xtx xxi xxx