a-a a-b a-c aaa aab aac aae aah aak aao ab- aba abb abc abe abh abk abo ac- aca acb acc ace ach ack aco aea aeb aec aee aeh aek aeo aha ahb ahc ahe ahh ahk aho aka akb akc ake akh akk ako aoa aob aoc aoe aoh aok aoo baa bab bac bae bah bak bao bba bbb bbc bbe bbh bbk bbo bca bcb bcc bce bch bck bco be- bea beb bec bee beh bek beo bha bhb bhc bhe bhh bhk bho bka bkb bkc bke bkk bko boa bob boc boe boh bok boo c-- caa cab cac cae cah cak cao cba cbb cbc cbe cbh cbk cbo cca ccb ccc cce cch cck cco ce- cea ceb cec cee ceh cek ceo ch- cha chb chc che chh chk cho cka ckb ckc ckh cko co- coa cob coc coe coh cok coo eaa eab eac eae eah eak eao eba ebb ebc ebe ebh ebk ebo ec- eca ecb ecc ece ech eck eco eea eeb eec eee eek eeo eha ehb ehc ehe ehh eho eka ekb ekc eke ekh eko eo- eoa eob eoc eoe eoh eok eoo haa hab hac hae hah hak hao hba hbb hbc hbe hbh hbk hbo hca hcb hcc hce hch hck hco he- hea heb hec hee heh hek heo hha hhb hhc hhe hhh hhk hho hka hkb hkh hkk hko hoa hob hoc hoe hoh hok hoo ka- kaa kab kac kae kah kak kao kba kbb kbc kbe kbh kbk kbo kca kcb kcc kce kch kck ke- kea keb kec kee keh kek keo kha khe khh khk kho kkb kkc kke kkh kkk koa kob koc koe koh kok koo oaa oab oac oae oah oak oao ob- oba obb obc obe obh obk obo oc- oca ocb occ och ock oco oea oeb oec oee oeh oeo oha ohc ohe ohh oho oka okb okc oke okk oko oo- ooa oob ooc ooh ook ooo