a-a a-b aaa aab aam aan aas ab- aba abb abm abn abs ama amb amm amn ams an- ana anb anm ann ans as- asa asb asm asn ass baa bab bam ban bas bba bbb bbm bbn bbs bma bmb bmm bmn bms bna bnb bnn bns bsa bsb bsm bsn bss maa mab mam man mas mba mbb mbm mbs mma mmb mmm mmn mms mna mnb mnm mnn mns msa msb msm msn mss naa nab nam nan nas nba nbb nbm nbn nbs nma nmb nmm nmn nms nna nnb nnm nnn nns nsa nsb nsm nsn nss saa sab sam san sas sba sbb sbm sbn sbs sma smb smm smn sms sna snb snm snn sns ss- ssa ssb ssm ssn sss