a-a a-b a-t aaa aab aad aar aat aax ab- aba abb abd abr abt abx ad- ada adb add adr adt adx ar- ara arb ard arr art arx at- ata atb atd atr att atx ax- axa axr axt axx baa bab bad bar bat bax bba bbb bbd bbr bbt bbx bda bdb bdd bdr bdt bdx bra brb brd brr brt brx bta btb btd btr btt btx bxb bxd bxx daa dab dad dar dat dax dba dbb dbd dbr dbt dbx dda ddb ddd ddr ddt ddx dra drb drd drr drt drx dta dtb dtd dtr dtt dtx dxd dxr dxt dxx ra- raa rab rad rar rat rax rba rbb rbd rbr rbt rbx rda rdb rdd rdr rdt rdx rra rrb rrd rrr rrt rta rtb rtd rtr rtt rtx rxr t-x taa tab tad tar tat tax tba tbb tbd tbr tbt tda tdb tdd tdr tdt tdx tra trb trd trr trt trx tta ttb ttd ttr ttt ttx txt xaa xad xar xat xbr xbx xda xdb xdr xdt xrd xrt xrx xtr xtx xxx