-er a-a a-b a-c aaa aab aac aae aah aak aao aar ab- aba abb abc abe abh abk abo abr ac- aca acb acc ace ach ack aco acr aea aeb aec aee aeh aek aeo aer aha ahb ahc ahe ahh ahk aho ahr aka akb akc ake akh akk ako akr aoa aob aoc aoe aoh aok aoo aor ar- ara arb arc are arh ark aro arr baa bab bac bae bah bak bao bar bba bbb bbc bbe bbh bbk bbo bbr bca bcb bcc bce bch bck bco bcr be- bea beb bec bee beh bek beo ber bha bhb bhc bhe bhh bhk bho bhr bka bkb bkc bke bkk bko bkr boa bob boc boe boh bok boo bor bra brb bre brh brk bro brr c-- caa cab cac cae cah cak cao car cba cbb cbc cbe cbh cbk cbo cbr cca ccb ccc cce cch cck cco ccr ce- cea ceb cec cee ceh cek ceo cer ch- cha chb chc che chh chk cho chr cka ckb ckc ckh cko co- coa cob coc coe coh cok coo cor cra crb crc cre crh crk cro crr eaa eab eac eae eah eak eao ear eba ebb ebc ebe ebh ebk ebo ebr ec- eca ecb ecc ece ech eck eco ecr eea eeb eec eee eek eeo eer eha ehb ehc ehe ehh eho ehr eka ekb ekc eke ekh eko ekr eo- eoa eob eoc eoe eoh eok eoo eor era erb erc ere erh erk ero err haa hab hac hae hah hak hao har hba hbb hbc hbe hbh hbk hbo hbr hca hcb hcc hce hch hck hco hcr he- hea heb hec hee heh hek heo her hha hhb hhc hhe hhh hhk hho hhr hka hkb hkh hkk hko hkr hoa hob hoc hoe hoh hok hoo hor hr- hra hrb hrc hre hrh hrk hro hrr ka- kaa kab kac kae kah kak kao kar kba kbb kbc kbe kbh kbk kbo kbr kca kcb kcc kce kch kck kcr ke- kea keb kec kee keh kek keo ker kha khe khh khk kho khr kkb kkc kke kkh kkk kkr koa kob koc koe koh kok koo kor kra krc krk kro krr oaa oab oac oae oah oak oao oar ob- oba obb obc obe obh obk obo obr oc- oca ocb occ och ock oco ocr oea oeb oec oee oeh oeo oer oha ohc ohe ohh oho ohr oka okb okc oke okk oko okr oo- ooa oob ooc ooh ook ooo oor or- ora orb orc ore orh ork oro orr ra- raa rab rac rae rah rak rao rar rba rbb rbc rbe rbh rbk rbo rbr rca rcb rcc rce rch rco rcr re- rea reb rec ree reh rek reo rer rh- rha rhb rhc rhe rhh rho rhr rkb rkc rke rkk rko roa rob roc roe roh rok roo ror rra rrb rrc rrh rrk rrr