a-a a-b aaa aab aam aao aar aas ab- aba abb abm abo abr abs ama amb amm amo amr ams aoa aob aom aoo aor aos ar- ara arb arm aro arr ars as- asa asb asm aso asr ass baa bab bam bao bar bas bba bbb bbm bbo bbr bbs bma bmb bmm bmo bmr bms boa bob bom boo bor bos bra brb brm bro brr brs bsa bsb bsm bso bsr bss m-o m-r maa mab mam mao mar mas mba mbb mbm mbo mbr mbs mma mmb mmm mmo mmr mms moa mob mom moo mor mos mra mrb mrm mro mrr mrs msa msb msm mso msr mss oaa oab oam oao oar oas ob- oba obb obm obo obr obs om- oma omb omm omo omr oms oo- ooa oob oom ooo oor oos or- ora orb orm oro orr ors os- osa osb osm oso osr oss ra- raa rab ram rao rar ras rba rbb rbm rbo rbr rbs rma rmb rmm rmo rmr rms roa rob rom roo ror ros rra rrb rrm rrr rrs rsa rsb rsm rso rsr rss saa sab sam sao sar sas sba sbb sbm sbo sbr sbs sma smb smm smo smr sms soa sob som soo sor sos sr- sra srb srm sro srr srs ss- ssa ssb ssm sso ssr sss