a-a a-b aaa aab aae aak aam aas ab- aba abb abe abk abm abs aea aeb aee aek aem aes aka akb ake akk akm aks ama amb ame amk amm ams as- asa asb ase ask asm ass baa bab bae bak bam bas bba bbb bbe bbk bbm bbs be- bea beb bee bek bem bes bka bkb bke bkk bkm bks bma bmb bme bmk bmm bms bsa bsb bse bsk bsm bss eaa eab eae eak eam eas eba ebb ebe ebk ebm ebs eea eeb eee eek eem ees eka ekb eke eks em- ema emb eme emk emm ems es- esa esb ese esk esm ess ka- kaa kab kae kak kam kas kba kbb kbe kbk kbm kbs ke- kea keb kee kek kem kes kkb kke kkk kkm kks kma kmb kme kmk kmm kms ksa ksb kse ksk ksm kss maa mab mae mak mam mas mba mbb mbe mbk mbm mbs mea meb mee mek mem mes mka mkb mke mkk mkm mks mma mmb mme mmk mmm mms msa msb mse msk msm mss saa sab sae sak sam sas sba sbb sbe sbk sbm sbs se- sea seb see sek sem ses sk- ska skb ske skk skm sks sma smb sme smk smm sms ss- ssa ssb sse ssk ssm sss