a-a a-b a-c aaa aab aac aak aan aau ab- aba abb abc abk abn abu ac- aca acb acc ack acn acu aka akb akc akk akn aku an- ana anb anc ank ann anu au- aua aub auc auk aun b-u baa bab bac bak ban bau bba bbb bbc bbk bbn bbu bca bcb bcc bck bcn bcu bka bkb bkc bkk bkn bna bnb bnc bnk bnn bnu bua bub buc buk bun buu c-- caa cab cac cak can cau cba cbb cbc cbk cbn cbu cca ccb ccc cck ccn ccu cka ckb ckc cn- cna cnb cnc cnn cnu cua cub cuc cuk cun cuu ka- kaa kab kac kak kan kau kba kbb kbc kbk kbn kbu kca kcb kcc kck kcn kcu kkb kkc kkk kkn kku kn- kna knc knk knn knu kub kuc kuk kun kuu naa nab nac nak nan nau nba nbb nbc nbk nbn nbu nca ncb ncc nck ncn ncu nka nkc nkk nkn nku nna nnb nnc nnk nnn nnu nua nub nuc nuk nun nuu ua- uaa uab uac uak uan uau uba ubb ubc ubk ubn ubu uca ucb ucc uck ucn ucu uka ukb ukc ukk ukn uku un- una unb unc unk unn unu uua uuc uun uuu