-er a-a a-b a-t aaa aab aae aak aan aao aar aat ab- aba abb abe abk abn abo abr abt aea aeb aee aek aen aeo aer aet aka akb ake akk akn ako akr an- ana anb ane ank ann ano anr ant aoa aob aoe aok aon aoo aor aot ar- ara arb are ark arn aro arr art at- ata atb ate atn ato atr att baa bab bae bak ban bao bar bat bba bbb bbe bbk bbn bbo bbr bbt be- bea beb bee bek ben beo ber bet bka bkb bke bkk bkn bko bkr bkt bna bnb bne bnk bnn bno bnr bnt boa bob boe bok bon boo bor bot bra brb bre brk brn bro brr brt bta btb bte btk btn bto btr btt eaa eab eae eak ean eao ear eat eba ebb ebe ebk ebn ebo ebr ebt eea eeb eee eek een eeo eer eet eka ekb eke eko ekr ekt en- ena enb ene enk enn eno enr ent eo- eoa eob eoe eok eon eoo eor eot era erb ere erk ern ero err ert eta etb ete etk etn eto etr ett k-t ka- kaa kab kae kak kan kao kar kat kba kbb kbe kbk kbn kbo kbr ke- kea keb kee kek ken keo ker ket kkb kke kkk kkn kkr kkt kn- kna kne knk knn kno knr knt koa kob koe kok kon koo kor kot kra krk krn kro krr krt kta ktb kte ktk ktn kto ktr ktt naa nab nae nak nan nao nar nat nba nbb nbe nbk nbn nbo nbr nbt ne- nea neb nee nek nen neo ner net nka nke nkk nkn nko nkr nkt nna nnb nne nnk nnn nno nnt no- noa nob noe nok non noo nor not nra nrb nre nrk nrn nro nrr nrt nta ntb nte ntk ntn nto ntr ntt oaa oab oae oak oan oao oar oat ob- oba obb obe obk obn obo obr obt oea oeb oee oen oeo oer oet oka okb oke okk oko okr on- ona onb one onk onn ono onr ont oo- ooa oob ook oon ooo oor oot or- ora orb ore ork orn oro orr ort ot- ota otb ote otk otn oto otr ott ra- raa rab rae rak ran rao rar rat rba rbb rbe rbk rbn rbo rbr rbt re- rea reb ree rek ren reo rer ret rkb rke rkk rko rkt rna rnb rnn rno rnr rnt roa rob roe rok ron roo ror rot rra rrb rrk rrn rrr rrt rta rtb rte rtk rtn rto rtr rtt taa tab tae tak tan tao tar tat tba tbb tbe tbk tbn tbo tbr tbt te- tea teb tee tek ten teo ter tet tka tkb tke tkk tko tkr tkt tna tnb tne tnk tnn tno tnr tnt to- toa tob toe tok ton too tor tot tra trb tre trk trn tro trr trt tta ttb tte ttk ttn tto ttr ttt