a-a a-b a-t aaa aab aaf aan aao aar aat ab- aba abb abf abn abo abr abt af- afa afb aff afn afo afr aft an- ana anb anf ann ano anr ant aoa aob aof aon aoo aor aot ar- ara arb arf arn aro arr art at- ata atb atf atn ato atr att baa bab baf ban bao bar bat bba bbb bbf bbn bbo bbr bbt bfa bfb bff bfn bfo bfr bft bna bnb bnf bnn bno bnr bnt boa bob bof bon boo bor bot bra brb brf brn bro brr brt bta btb btf btn bto btr btt faa fab faf fan fao far fat fba fbb fbf fbn fbo fbr fbt ffa fff ffn ffo ffr fft fna fnb fnf fnn fnr fnt foa fob fof fon foo for fot fra frb frf frn fro frr frt fta ftb ftf ftn fto ftr ftt naa nab naf nan nao nar nat nba nbb nbf nbn nbo nbr nbt nfa nfb nff nfn nfo nfr nft nna nnb nnf nnn nno nnt no- noa nob nof non noo nor not nra nrb nrf nrn nro nrr nrt nta ntb ntf ntn nto ntr ntt oaa oab oaf oan oao oar oat ob- oba obb obf obn obo obr obt of- ofa ofb off ofn ofo ofr oft on- ona onb onf onn ono onr ont oo- ooa oob oof oon ooo oor oot or- ora orb orf orn oro orr ort ot- ota otb otf otn oto otr ott ra- raa rab raf ran rao rar rat rba rbb rbf rbn rbo rbr rbt rfa rfb rff rfn rfo rfr rft rna rnb rnn rno rnr rnt roa rob rof ron roo ror rot rra rrb rrf rrn rrr rrt rta rtb rtf rtn rto rtr rtt taa tab taf tan tao tar tat tba tbb tbf tbn tbo tbr tbt tfa tfb tff tfn tfo tfr tft tna tnb tnf tnn tno tnr tnt to- toa tob tof ton too tor tot tra trb trf trn tro trr trt tta ttb ttf ttn tto ttr ttt