a-a a-b aaa aab aak aam aas ab- aba abb abk abm abs aka akb akk akm aks ama amb amk amm ams as- asa asb ask asm ass baa bab bak bam bas bba bbb bbk bbm bbs bka bkb bkk bkm bks bma bmb bmk bmm bms bsa bsb bsk bsm bss ka- kaa kab kak kam kas kba kbb kbk kbm kbs kkb kkk kkm kks kma kmb kmk kmm kms ksa ksb ksk ksm kss maa mab mak mam mas mba mbb mbk mbm mbs mka mkb mkk mkm mks mma mmb mmk mmm mms msa msb msk msm mss saa sab sak sam sas sba sbb sbk sbm sbs sk- ska skb skk skm sks sma smb smk smm sms ss- ssa ssb ssk ssm sss