a-a a-b a-c aaa aab aac aam aao aar aas ab- aba abb abc abm abo abr abs ac- aca acb acc acm aco acr acs ama amb amc amm amo amr ams aoa aob aoc aom aoo aor aos ar- ara arb arc arm aro arr ars as- asa asb asc asm aso asr ass baa bab bac bam bao bar bas bba bbb bbc bbm bbo bbr bbs bca bcb bcc bcm bco bcr bcs bma bmb bmc bmm bmo bmr bms boa bob boc bom boo bor bos bra brb brm bro brr brs bsa bsb bsc bsm bso bsr bss c-- caa cab cac cam cao car cas cba cbb cbc cbm cbo cbr cbs cca ccb ccc ccm cco ccr ccs cma cmb cmc cmm cmo cmr cms co- coa cob coc com coo cor cos cra crb crc crm cro crr crs csa csb csc csm cso csr css m-o m-r maa mab mac mam mao mar mas mba mbb mbc mbm mbo mbr mbs mc- mca mcb mcc mcm mco mcr mcs mma mmb mmc mmm mmo mmr mms moa mob moc mom moo mor mos mra mrb mrc mrm mro mrr mrs msa msb msc msm mso msr mss oaa oab oac oam oao oar oas ob- oba obb obc obm obo obr obs oc- oca ocb occ ocm oco ocr ocs om- oma omb omc omm omo omr oms oo- ooa oob ooc oom ooo oor oos or- ora orb orc orm oro orr ors os- osa osb osc osm oso osr oss ra- raa rab rac ram rao rar ras rba rbb rbc rbm rbo rbr rbs rca rcb rcc rcm rco rcr rcs rma rmb rmc rmm rmo rmr rms roa rob roc rom roo ror ros rra rrb rrc rrm rrr rrs rsa rsb rsc rsm rso rsr rss saa sab sac sam sao sar sas sba sbb sbc sbm sbo sbr sbs sca scb scc scm sco scr scs sma smb smc smm smo smr sms soa sob soc som soo sor sos sr- sra srb src srm sro srr srs ss- ssa ssb ssc ssm sso ssr sss