a-a a-b a-c aaa aab aac aae aah aak ab- aba abb abc abe abh abk ac- aca acb acc ace ach ack aea aeb aec aee aeh aek aha ahb ahc ahe ahh ahk aka akb akc ake akh akk baa bab bac bae bah bak bba bbb bbc bbe bbh bbk bca bcb bcc bce bch bck be- bea beb bec bee beh bek bha bhb bhc bhe bhh bhk bka bkb bkc bke bkk c-- caa cab cac cae cah cak cba cbb cbc cbe cbh cbk cca ccb ccc cce cch cck ce- cea ceb cec cee ceh cek ch- cha chb chc che chh chk cka ckb ckc ckh eaa eab eac eae eah eak eba ebb ebc ebe ebh ebk ec- eca ecb ecc ece ech eck eea eeb eec eee eek eha ehb ehc ehe ehh eka ekb ekc eke ekh haa hab hac hae hah hak hba hbb hbc hbe hbh hbk hca hcb hcc hce hch hck he- hea heb hec hee heh hek hha hhb hhc hhe hhh hhk hka hkb hkh hkk ka- kaa kab kac kae kah kak kba kbb kbc kbe kbh kbk kca kcb kcc kce kch kck ke- kea keb kec kee keh kek kha khe khh khk kkb kkc kke kkh kkk