a-a a-b a-c aaa aab aac aae aah aao ab- aba abb abc abe abh abo ac- aca acb acc ace ach aco aea aeb aec aee aeh aeo aha ahb ahc ahe ahh aho aoa aob aoc aoe aoh aoo baa bab bac bae bah bao bba bbb bbc bbe bbh bbo bca bcb bcc bce bch bco be- bea beb bec bee beh beo bha bhb bhc bhe bhh bho boa bob boc boe boh boo c-- caa cab cac cae cah cao cba cbb cbc cbe cbh cbo cca ccb ccc cce cch cco ce- cea ceb cec cee ceh ceo ch- cha chb chc che chh cho co- coa cob coc coe coh coo eaa eab eac eae eah eao eba ebb ebc ebe ebh ebo ec- eca ecb ecc ece ech eco eea eeb eec eee eeo eha ehb ehc ehe ehh eho eo- eoa eob eoc eoe eoh eoo haa hab hac hae hah hao hba hbb hbc hbe hbh hbo hca hcb hcc hce hch hco he- hea heb hec hee heh heo hha hhb hhc hhe hhh hho hoa hob hoc hoe hoh hoo oaa oab oac oae oah oao ob- oba obb obc obe obh obo oc- oca ocb occ och oco oea oeb oec oee oeh oeo oha ohc ohe ohh oho oo- ooa oob ooc ooh ooo