a-a a-b a-c aaa aab aac aae aak aam aan ab- aba abb abc abe abk abm abn ac- aca acb acc ace ack acm acn aea aeb aec aee aek aem aen aka akb akc ake akk akm akn ama amb amc ame amk amm amn an- ana anb anc ane ank anm ann baa bab bac bae bak bam ban bba bbb bbc bbe bbk bbm bbn bca bcb bcc bce bck bcm bcn be- bea beb bec bee bek bem ben bka bkb bkc bke bkk bkm bkn bma bmb bmc bme bmk bmm bmn bna bnb bnc bne bnk bnn c-- caa cab cac cae cak cam can cba cbb cbc cbe cbk cbm cbn cca ccb ccc cce cck ccm ccn ce- cea ceb cec cee cek cem cen cka ckb ckc ckm cma cmb cmc cme cmk cmm cmn cn- cna cnb cnc cne cnm cnn eaa eab eac eae eak eam ean eba ebb ebc ebe ebk ebm ebn ec- eca ecb ecc ece eck ecm ecn eea eeb eec eee eek eem een eka ekb ekc eke em- ema emb emc eme emk emm emn en- ena enb enc ene enk enm enn ka- kaa kab kac kae kak kam kan kba kbb kbc kbe kbk kbm kbn kca kcb kcc kce kck kcm kcn ke- kea keb kec kee kek kem ken kkb kkc kke kkk kkm kkn kma kmb kmc kme kmk kmm kn- kna knc kne knk knm knn maa mab mac mae mak mam man mba mbb mbc mbe mbk mbm mc- mca mcb mcc mce mck mcm mcn mea meb mec mee mek mem men mka mkb mkc mke mkk mkm mkn mma mmb mmc mme mmk mmm mmn mna mnb mnc mne mnk mnm mnn naa nab nac nae nak nam nan nba nbb nbc nbe nbk nbm nbn nca ncb ncc nce nck ncm ncn ne- nea neb nec nee nek nem nen nka nkc nke nkk nkm nkn nma nmb nmc nme nmk nmm nmn nna nnb nnc nne nnk nnm nnn