-er a-a a-b aaa aab aae aag aak aan aao aar ab- aba abb abe abg abk abn abo abr aea aeb aee aeg aek aen aeo aer ag- aga agb age agg agk agn ago agr aka akb ake akg akk akn ako akr an- ana anb ane ang ank ann ano anr aoa aob aoe aog aok aon aoo aor ar- ara arb are arg ark arn aro arr baa bab bae bag bak ban bao bar bba bbb bbe bbg bbk bbn bbo bbr be- bea beb bee beg bek ben beo ber bga bgb bge bgg bgk bgn bgo bgr bka bkb bke bkg bkk bkn bko bkr bna bnb bne bng bnk bnn bno bnr boa bob boe bog bok bon boo bor bra brb bre brg brk brn bro brr eaa eab eae eag eak ean eao ear eba ebb ebe ebg ebk ebn ebo ebr eea eeb eee eeg eek een eeo eer ega egb ege egg egn ego egr eka ekb eke ekg eko ekr en- ena enb ene eng enk enn eno enr eo- eoa eob eoe eog eok eon eoo eor era erb ere erg erk ern ero err gaa gab gae gag gak gan gao gar gba gbe gbg gbk gbn gbo gbr ge- gea geb gee geg gek gen geo ger gga ggb ggg ggn ggo ggr gka gkb gkn gko gna gnb gne gnn gno gnr goa gob goe gog gok gon goo gor gra grb gre grg grk grn gro grr ka- kaa kab kae kag kak kan kao kar kba kbb kbe kbk kbn kbo kbr ke- kea keb kee keg kek ken keo ker kga kgb kgo kkb kke kkk kkn kkr kn- kna kne kng knk knn kno knr koa kob koe kog kok kon koo kor kra krg krk krn kro krr naa nab nae nag nak nan nao nar nba nbb nbe nbg nbk nbn nbo nbr ne- nea neb nee neg nek nen neo ner nga ngb nge ngg ngk ngn ngo nka nke nkk nkn nko nkr nna nnb nne nng nnk nnn nno no- noa nob noe nog nok non noo nor nra nrb nre nrg nrk nrn nro nrr oaa oab oae oag oak oan oao oar ob- oba obb obe obg obk obn obo obr oea oeb oee oeg oen oeo oer oga oge ogg ogn ogo oka okb oke okg okk oko okr on- ona onb one ong onk onn ono onr oo- ooa oob oog ook oon ooo oor or- ora orb ore org ork orn oro orr ra- raa rab rae rag rak ran rao rar rba rbb rbe rbg rbk rbn rbo rbr re- rea reb ree reg rek ren reo rer rga rgb rge rgg rgk rgn rgo rgr rkb rke rkg rkk rko rna rnb rng rnn rno rnr roa rob roe rog rok ron roo ror rra rrb rrg rrk rrn rrr