a-a a-b a-c aaa aab aac aam aas ab- aba abb abc abm abs ac- aca acb acc acm acs ama amb amc amm ams as- asa asb asc asm ass baa bab bac bam bas bba bbb bbc bbm bbs bca bcb bcc bcm bcs bma bmb bmc bmm bms bsa bsb bsc bsm bss c-- caa cab cac cam cas cba cbb cbc cbm cbs cca ccb ccc ccm ccs cma cmb cmc cmm cms csa csb csc csm css maa mab mac mam mas mba mbb mbc mbm mbs mc- mca mcb mcc mcm mcs mma mmb mmc mmm mms msa msb msc msm mss saa sab sac sam sas sba sbb sbc sbm sbs sca scb scc scm scs sma smb smc smm sms ss- ssa ssb ssc ssm sss