a-a a-b a-c aaa aab aac aaf aah aan ab- aba abb abc abf abh abn ac- aca acb acc acf ach acn af- afa afb afc aff afh afn aha ahb ahc ahf ahh ahn an- ana anb anc anf anh ann baa bab bac baf bah ban bba bbb bbc bbf bbh bbn bca bcb bcc bcf bch bcn bfa bfb bfc bff bfh bfn bha bhb bhc bhf bhh bna bnb bnc bnf bnn c-- caa cab cac caf cah can cba cbb cbc cbf cbh cbn cca ccb ccc ccf cch ccn cfa cfb cfc cff cfh cfn ch- cha chb chc chf chh chn cn- cna cnb cnc cnf cnh cnn faa fab fac faf fah fan fba fbb fbc fbf fbh fbn fca fcb fcc fcf fcn ffa ffc fff ffh ffn fha fhb fhc fhf fhh fhn fna fnb fnc fnf fnh fnn haa hab hac haf hah han hba hbb hbc hbf hbh hbn hca hcb hcc hcf hch hcn hfa hfb hfc hff hfh hfn hha hhb hhc hhf hhh hhn hna hnb hnc hnf hnh hnn naa nab nac naf nah nan nba nbb nbc nbf nbn nca ncb ncc ncf nch ncn nfa nfb nfc nff nfn nha nhb nhc nhf nhh nhn nna nnb nnc nnf nnh nnn