-er a-a a-b a-c aaa aab aac aae aah aao aar ab- aba abb abc abe abh abo abr ac- aca acb acc ace ach aco acr aea aeb aec aee aeh aeo aer aha ahb ahc ahe ahh aho ahr aoa aob aoc aoe aoh aoo aor ar- ara arb arc are arh aro arr baa bab bac bae bah bao bar bba bbb bbc bbe bbh bbo bbr bca bcb bcc bce bch bco bcr be- bea beb bec bee beh beo ber bha bhb bhc bhe bhh bho bhr boa bob boc boe boh boo bor bra brb bre brh bro brr c-- caa cab cac cae cah cao car cba cbb cbc cbe cbh cbo cbr cca ccb ccc cce cch cco ccr ce- cea ceb cec cee ceh ceo cer ch- cha chb chc che chh cho chr co- coa cob coc coe coh coo cor cra crb crc cre crh cro crr eaa eab eac eae eah eao ear eba ebb ebc ebe ebh ebo ebr ec- eca ecb ecc ece ech eco ecr eea eeb eec eee eeo eer eha ehb ehc ehe ehh eho ehr eo- eoa eob eoc eoe eoh eoo eor era erb erc ere erh ero err haa hab hac hae hah hao har hba hbb hbc hbe hbh hbo hbr hca hcb hcc hce hch hco hcr he- hea heb hec hee heh heo her hha hhb hhc hhe hhh hho hhr hoa hob hoc hoe hoh hoo hor hr- hra hrb hrc hre hrh hro hrr oaa oab oac oae oah oao oar ob- oba obb obc obe obh obo obr oc- oca ocb occ och oco ocr oea oeb oec oee oeh oeo oer oha ohc ohe ohh oho ohr oo- ooa oob ooc ooh ooo oor or- ora orb orc ore orh oro orr ra- raa rab rac rae rah rao rar rba rbb rbc rbe rbh rbo rbr rca rcb rcc rce rch rco rcr re- rea reb rec ree reh reo rer rh- rha rhb rhc rhe rhh rho rhr roa rob roc roe roh roo ror rra rrb rrc rrh rrr