a-a a-b aaa aab aae aah aao ab- aba abb abe abh abo aea aeb aee aeh aeo aha ahb ahe ahh aho aoa aob aoe aoh aoo baa bab bae bah bao bba bbb bbe bbh bbo be- bea beb bee beh beo bha bhb bhe bhh bho boa bob boe boh boo eaa eab eae eah eao eba ebb ebe ebh ebo eea eeb eee eeo eha ehb ehe ehh eho eo- eoa eob eoe eoh eoo haa hab hae hah hao hba hbb hbe hbh hbo he- hea heb hee heh heo hha hhb hhe hhh hho hoa hob hoe hoh hoo oaa oab oae oah oao ob- oba obb obe obh obo oea oeb oee oeh oeo oha ohe ohh oho oo- ooa oob ooh ooo