-er a-a a-b a-i a-t aaa aab aae aai aak aao aar aat ab- aba abb abe abi abk abo abr abt aea aeb aee aei aek aeo aer aet ai- aia aib aie aii aik aio air ait aka akb ake aki akk ako akr aoa aob aoe aoi aok aoo aor aot ar- ara arb are ari ark aro arr art at- ata atb ate ati ato atr att baa bab bae bai bak bao bar bat bba bbb bbe bbi bbk bbo bbr bbt be- bea beb bee bei bek beo ber bet bi- bia bib bie bii bik bio bir bit bka bkb bke bkk bko bkr bkt boa bob boe boi bok boo bor bot bra brb bre bri brk bro brr brt bta btb bte bti btk bto btr btt eaa eab eae eai eak eao ear eat eba ebb ebe ebi ebk ebo ebr ebt eea eeb eee eek eeo eer eet eia eib eie eii eik eio eir eit eka ekb eke eki eko ekr ekt eo- eoa eob eoe eoi eok eoo eor eot era erb ere eri erk ero err ert eta etb ete eti etk eto etr ett ia- iaa iab iae iai iao iar iat iba ibb ibe ibi ibk ibo ibr ibt ie- iea iee iei iek ier iet iia iib iie iii iio iir iit ika ikb ike iki ikk iko ikr ikt io- ioa iob ioe ioi ioo ior iot ir- ira irb ire iri irk iro irr irt ita itb ite iti itk ito itt k-t ka- kaa kab kae kai kak kao kar kat kba kbb kbe kbi kbk kbo kbr ke- kea keb kee kei kek keo ker ket kia kib kie kii kik kio kir kit kkb kke kki kkk kkr kkt koa kob koe koi kok koo kor kot kra kri krk kro krr krt kta ktb kte ktk kto ktr ktt o-i oaa oab oae oai oak oao oar oat ob- oba obb obe obi obk obo obr obt oea oeb oee oei oeo oer oet oia oib oie oii oik oio oir oit oka okb oke oki okk oko okr oo- ooa oob ooi ook ooo oor oot or- ora orb ore ori ork oro orr ort ot- ota otb ote oti otk oto otr ott ra- raa rab rae rai rak rao rar rat rba rbb rbe rbi rbk rbo rbr rbt re- rea reb ree rei rek reo rer ret ria rib rie rii rik rio rir rit rkb rke rkk rko rkt roa rob roe roi rok roo ror rot rra rrb rri rrk rrr rrt rta rtb rte rti rtk rto rtr rtt taa tab tae tai tak tao tar tat tba tbb tbe tbi tbk tbo tbr tbt te- tea teb tee tei tek teo ter tet tia tib tie tii tik tio tir tit tka tkb tke tkk tko tkr tkt to- toa tob toe toi tok too tor tot tra trb tre tri trk tro trr trt tta ttb tte tti ttk tto ttr ttt