a-a a-b aaa aab aam aar aas aax ab- aba abb abm abr abs abx ama amb amm amr ams amx ar- ara arb arm arr ars arx as- asa asb asm asr ass asx ax- axa axm axr axs axx baa bab bam bar bas bax bba bbb bbm bbr bbs bbx bma bmb bmm bmr bms bmx bra brb brm brr brs brx bsa bsb bsm bsr bss bsx bxb bxm bxx m-r maa mab mam mar mas max mba mbb mbm mbr mbs mbx mma mmb mmm mmr mms mmx mra mrb mrm mrr mrs mrx msa msb msm msr mss msx mxa mxr mxs ra- raa rab ram rar ras rax rba rbb rbm rbr rbs rbx rma rmb rmm rmr rms rmx rra rrb rrm rrr rrs rsa rsb rsm rsr rss rsx rxr rxs saa sab sam sar sas sax sba sbb sbm sbr sbs sbx sma smb smm smr sms smx sr- sra srb srm srr srs srx ss- ssa ssb ssm ssr sss ssx sxm sxs xaa xam xar xas xbr xbx xma xmm xmr xms xmx xrx xsa xsb xsm xss xxx