a-a a-b a-c aaa aab aac aah aak ab- aba abb abc abh abk ac- aca acb acc ach ack aha ahb ahc ahh ahk aka akb akc akh akk baa bab bac bah bak bba bbb bbc bbh bbk bca bcb bcc bch bck bha bhb bhc bhh bhk bka bkb bkc bkk c-- caa cab cac cah cak cba cbb cbc cbh cbk cca ccb ccc cch cck ch- cha chb chc chh chk cka ckb ckc ckh haa hab hac hah hak hba hbb hbc hbh hbk hca hcb hcc hch hck hha hhb hhc hhh hhk hka hkb hkh hkk ka- kaa kab kac kah kak kba kbb kbc kbh kbk kca kcb kcc kch kck kha khh khk kkb kkc kkh kkk