a-a a-b a-c aaa aab aac aah aao aar ab- aba abb abc abh abo abr ac- aca acb acc ach aco acr aha ahb ahc ahh aho ahr aoa aob aoc aoh aoo aor ar- ara arb arc arh aro arr baa bab bac bah bao bar bba bbb bbc bbh bbo bbr bca bcb bcc bch bco bcr bha bhb bhc bhh bho bhr boa bob boc boh boo bor bra brb brh bro brr c-- caa cab cac cah cao car cba cbb cbc cbh cbo cbr cca ccb ccc cch cco ccr ch- cha chb chc chh cho chr co- coa cob coc coh coo cor cra crb crc crh cro crr haa hab hac hah hao har hba hbb hbc hbh hbo hbr hca hcb hcc hch hco hcr hha hhb hhc hhh hho hhr hoa hob hoc hoh hoo hor hr- hra hrb hrc hrh hro hrr oaa oab oac oah oao oar ob- oba obb obc obh obo obr oc- oca ocb occ och oco ocr oha ohc ohh oho ohr oo- ooa oob ooc ooh ooo oor or- ora orb orc orh oro orr ra- raa rab rac rah rao rar rba rbb rbc rbh rbo rbr rca rcb rcc rch rco rcr rh- rha rhb rhc rhh rho rhr roa rob roc roh roo ror rra rrb rrc rrh rrr