-er a-a a-b aaa aab aae aam aar aax ab- aba abb abe abm abr abx aea aeb aee aem aer aex ama amb ame amm amr amx ar- ara arb are arm arr arx ax- axa axe axm axr axx baa bab bae bam bar bax bba bbb bbe bbm bbr bbx be- bea beb bee bem ber bex bma bmb bme bmm bmr bmx bra brb bre brm brr brx bxb bxm bxx eaa eab eae eam ear eax eba ebb ebe ebm ebr ebx eea eeb eee eem eer eex em- ema emb eme emm emr emx era erb ere erm err ex- exa exe exr exx m-r maa mab mae mam mar max mba mbb mbe mbm mbr mbx mea meb mee mem mer mex mma mmb mme mmm mmr mmx mra mrb mre mrm mrr mrx mxa mxr ra- raa rab rae ram rar rax rba rbb rbe rbm rbr rbx re- rea reb ree rem rer rex rma rmb rme rmm rmr rmx rra rrb rrm rrr rxr xaa xam xar xbe xbr xbx xee xem xer xex xma xmm xmr xmx xrx xxx