a-a a-b a-c aaa aab aac aaf aah aao aar ab- aba abb abc abf abh abo abr ac- aca acb acc acf ach aco acr af- afa afb afc aff afh afo afr aha ahb ahc ahf ahh aho ahr aoa aob aoc aof aoh aoo aor ar- ara arb arc arf arh aro arr baa bab bac baf bah bao bar bba bbb bbc bbf bbh bbo bbr bca bcb bcc bcf bch bco bcr bfa bfb bfc bff bfh bfo bfr bha bhb bhc bhf bhh bho bhr boa bob boc bof boh boo bor bra brb brf brh bro brr c-- caa cab cac caf cah cao car cba cbb cbc cbf cbh cbo cbr cca ccb ccc ccf cch cco ccr cfa cfb cfc cff cfh cfo cfr ch- cha chb chc chf chh cho chr co- coa cob coc cof coh coo cor cra crb crc crf crh cro crr faa fab fac faf fah fao far fba fbb fbc fbf fbh fbo fbr fca fcb fcc fcf fco fcr ffa ffc fff ffh ffo ffr fha fhb fhc fhf fhh fho fhr foa fob foc fof foh foo for fra frb frc frf frh fro frr haa hab hac haf hah hao har hba hbb hbc hbf hbh hbo hbr hca hcb hcc hcf hch hco hcr hfa hfb hfc hff hfh hfo hfr hha hhb hhc hhf hhh hho hhr hoa hob hoc hof hoh hoo hor hr- hra hrb hrc hrf hrh hro hrr oaa oab oac oaf oah oao oar ob- oba obb obc obf obh obo obr oc- oca ocb occ ocf och oco ocr of- ofa ofb ofc off ofo ofr oha ohc ohf ohh oho ohr oo- ooa oob ooc oof ooh ooo oor or- ora orb orc orf orh oro orr ra- raa rab rac raf rah rao rar rba rbb rbc rbf rbh rbo rbr rca rcb rcc rcf rch rco rcr rfa rfb rfc rff rfh rfo rfr rh- rha rhb rhc rhf rhh rho rhr roa rob roc rof roh roo ror rra rrb rrc rrf rrh rrr