a-a a-b a-t aaa aab aan aao aar aat ab- aba abb abn abo abr abt an- ana anb ann ano anr ant aoa aob aon aoo aor aot ar- ara arb arn aro arr art at- ata atb atn ato atr att baa bab ban bao bar bat bba bbb bbn bbo bbr bbt bna bnb bnn bno bnr bnt boa bob bon boo bor bot bra brb brn bro brr brt bta btb btn bto btr btt naa nab nan nao nar nat nba nbb nbn nbo nbr nbt nna nnb nnn nno nnt no- noa nob non noo nor not nra nrb nrn nro nrr nrt nta ntb ntn nto ntr ntt oaa oab oan oao oar oat ob- oba obb obn obo obr obt on- ona onb onn ono onr ont oo- ooa oob oon ooo oor oot or- ora orb orn oro orr ort ot- ota otb otn oto otr ott ra- raa rab ran rao rar rat rba rbb rbn rbo rbr rbt rna rnb rnn rno rnr rnt roa rob ron roo ror rot rra rrb rrn rrr rrt rta rtb rtn rto rtr rtt taa tab tan tao tar tat tba tbb tbn tbo tbr tbt tna tnb tnn tno tnr tnt to- toa tob ton too tor tot tra trb trn tro trr trt tta ttb ttn tto ttr ttt