a-a a-b a-c aaa aab aac aae aam aao aas ab- aba abb abc abe abm abo abs ac- aca acb acc ace acm aco acs aea aeb aec aee aem aeo aes ama amb amc ame amm amo ams aoa aob aoc aoe aom aoo aos as- asa asb asc ase asm aso ass baa bab bac bae bam bao bas bba bbb bbc bbe bbm bbo bbs bca bcb bcc bce bcm bco bcs be- bea beb bec bee bem beo bes bma bmb bmc bme bmm bmo bms boa bob boc boe bom boo bos bsa bsb bsc bse bsm bso bss c-- caa cab cac cae cam cao cas cba cbb cbc cbe cbm cbo cbs cca ccb ccc cce ccm cco ccs ce- cea ceb cec cee cem ceo ces cma cmb cmc cme cmm cmo cms co- coa cob coc coe com coo cos csa csb csc cse csm cso css eaa eab eac eae eam eao eas eba ebb ebc ebe ebm ebo ebs ec- eca ecb ecc ece ecm eco ecs eea eeb eec eee eem eeo ees em- ema emb emc eme emm emo ems eo- eoa eob eoc eoe eom eoo eos es- esa esb esc ese esm eso ess m-o maa mab mac mae mam mao mas mba mbb mbc mbe mbm mbo mbs mc- mca mcb mcc mce mcm mco mcs mea meb mec mee mem meo mes mma mmb mmc mme mmm mmo mms moa mob moc moe mom moo mos msa msb msc mse msm mso mss oaa oab oac oae oam oao oas ob- oba obb obc obe obm obo obs oc- oca ocb occ ocm oco ocs oea oeb oec oee oem oeo oes om- oma omb omc ome omm omo oms oo- ooa oob ooc oom ooo oos os- osa osb osc ose osm oso oss saa sab sac sae sam sao sas sba sbb sbc sbe sbm sbo sbs sca scb scc sce scm sco scs se- sea seb sec see sem seo ses sma smb smc sme smm smo sms soa sob soc soe som soo sos ss- ssa ssb ssc sse ssm sso sss