a-a a-b aaa aab aam aas aax ab- aba abb abm abs abx ama amb amm ams amx as- asa asb asm ass asx ax- axa axm axs axx baa bab bam bas bax bba bbb bbm bbs bbx bma bmb bmm bms bmx bsa bsb bsm bss bsx bxb bxm bxx maa mab mam mas max mba mbb mbm mbs mbx mma mmb mmm mms mmx msa msb msm mss msx mxa mxs saa sab sam sas sax sba sbb sbm sbs sbx sma smb smm sms smx ss- ssa ssb ssm sss ssx sxm sxs xaa xam xas xbx xma xmm xms xmx xsa xsb xsm xss xxx