a-a a-b a-c aaa aab aac aae aah aan ab- aba abb abc abe abh abn ac- aca acb acc ace ach acn aea aeb aec aee aeh aen aha ahb ahc ahe ahh ahn an- ana anb anc ane anh ann baa bab bac bae bah ban bba bbb bbc bbe bbh bbn bca bcb bcc bce bch bcn be- bea beb bec bee beh ben bha bhb bhc bhe bhh bna bnb bnc bne bnn c-- caa cab cac cae cah can cba cbb cbc cbe cbh cbn cca ccb ccc cce cch ccn ce- cea ceb cec cee ceh cen ch- cha chb chc che chh chn cn- cna cnb cnc cne cnh cnn eaa eab eac eae eah ean eba ebb ebc ebe ebh ebn ec- eca ecb ecc ece ech ecn eea eeb eec eee een eha ehb ehc ehe ehh ehn en- ena enb enc ene enh enn haa hab hac hae hah han hba hbb hbc hbe hbh hbn hca hcb hcc hce hch hcn he- hea heb hec hee heh hen hha hhb hhc hhe hhh hhn hna hnb hnc hne hnh hnn naa nab nac nae nah nan nba nbb nbc nbe nbn nca ncb ncc nce nch ncn ne- nea neb nec nee neh nen nha nhb nhc nhe nhh nhn nna nnb nnc nne nnh nnn