-er a-a a-b a-t aaa aab aae aan aao aar aat ab- aba abb abe abn abo abr abt aea aeb aee aen aeo aer aet an- ana anb ane ann ano anr ant aoa aob aoe aon aoo aor aot ar- ara arb are arn aro arr art at- ata atb ate atn ato atr att baa bab bae ban bao bar bat bba bbb bbe bbn bbo bbr bbt be- bea beb bee ben beo ber bet bna bnb bne bnn bno bnr bnt boa bob boe bon boo bor bot bra brb bre brn bro brr brt bta btb bte btn bto btr btt eaa eab eae ean eao ear eat eba ebb ebe ebn ebo ebr ebt eea eeb eee een eeo eer eet en- ena enb ene enn eno enr ent eo- eoa eob eoe eon eoo eor eot era erb ere ern ero err ert eta etb ete etn eto etr ett naa nab nae nan nao nar nat nba nbb nbe nbn nbo nbr nbt ne- nea neb nee nen neo ner net nna nnb nne nnn nno nnt no- noa nob noe non noo nor not nra nrb nre nrn nro nrr nrt nta ntb nte ntn nto ntr ntt oaa oab oae oan oao oar oat ob- oba obb obe obn obo obr obt oea oeb oee oen oeo oer oet on- ona onb one onn ono onr ont oo- ooa oob oon ooo oor oot or- ora orb ore orn oro orr ort ot- ota otb ote otn oto otr ott ra- raa rab rae ran rao rar rat rba rbb rbe rbn rbo rbr rbt re- rea reb ree ren reo rer ret rna rnb rnn rno rnr rnt roa rob roe ron roo ror rot rra rrb rrn rrr rrt rta rtb rte rtn rto rtr rtt taa tab tae tan tao tar tat tba tbb tbe tbn tbo tbr tbt te- tea teb tee ten teo ter tet tna tnb tne tnn tno tnr tnt to- toa tob toe ton too tor tot tra trb tre trn tro trr trt tta ttb tte ttn tto ttr ttt