a-a a-b a-c aaa aab aac aam aar aas ab- aba abb abc abm abr abs ac- aca acb acc acm acr acs ama amb amc amm amr ams ar- ara arb arc arm arr ars as- asa asb asc asm asr ass baa bab bac bam bar bas bba bbb bbc bbm bbr bbs bca bcb bcc bcm bcr bcs bma bmb bmc bmm bmr bms bra brb brm brr brs bsa bsb bsc bsm bsr bss c-- caa cab cac cam car cas cba cbb cbc cbm cbr cbs cca ccb ccc ccm ccr ccs cma cmb cmc cmm cmr cms cra crb crc crm crr crs csa csb csc csm csr css m-r maa mab mac mam mar mas mba mbb mbc mbm mbr mbs mc- mca mcb mcc mcm mcr mcs mma mmb mmc mmm mmr mms mra mrb mrc mrm mrr mrs msa msb msc msm msr mss ra- raa rab rac ram rar ras rba rbb rbc rbm rbr rbs rca rcb rcc rcm rcr rcs rma rmb rmc rmm rmr rms rra rrb rrc rrm rrr rrs rsa rsb rsc rsm rsr rss saa sab sac sam sar sas sba sbb sbc sbm sbr sbs sca scb scc scm scr scs sma smb smc smm smr sms sr- sra srb src srm srr srs ss- ssa ssb ssc ssm ssr sss