a-a a-b a-c aaa aab aac aad aak aar aas ab- aba abb abc abd abk abr abs ac- aca acb acc acd ack acr acs ad- ada adb adc add adk adr ads aka akb akc akd akk akr aks ar- ara arb arc ard ark arr ars as- asa asb asc asd ask asr ass baa bab bac bad bak bar bas bba bbb bbc bbd bbk bbr bbs bca bcb bcc bcd bck bcr bcs bda bdb bdc bdd bdk bdr bds bka bkb bkc bkk bkr bks bra brb brd brk brr brs bsa bsb bsc bsd bsk bsr bss c-- caa cab cac cad cak car cas cba cbb cbc cbd cbk cbr cbs cca ccb ccc ccd cck ccr ccs cda cdb cdc cdd cdk cdr cds cka ckb ckc ckd cks cra crb crc crd crk crr crs csa csb csc csd csk csr css daa dab dac dad dak dar das dba dbb dbc dbd dbk dbr dbs dca dcb dcc dcd dck dcr dcs dda ddb ddc ddd ddk ddr dds dka dkb dkc dkk dkr dks dra drb drc drd drk drr drs dsa dsb dsc dsd dsk dsr dss ka- kaa kab kac kad kak kar kas kba kbb kbc kbd kbk kbr kbs kca kcb kcc kcd kck kcr kcs kda kdb kdc kdk kdr kds kkb kkc kkk kkr kks kra krc krd krk krr krs ksa ksb ksc ksd ksk ksr kss ra- raa rab rac rad rak rar ras rba rbb rbc rbd rbk rbr rbs rca rcb rcc rcd rcr rcs rda rdb rdc rdd rdr rds rkb rkc rkk rks rra rrb rrc rrd rrk rrr rrs rsa rsb rsc rsd rsk rsr rss saa sab sac sad sak sar sas sba sbb sbc sbd sbk sbr sbs sca scb scc scd sck scr scs sda sdb sdc sdd sdk sdr sds sk- ska skb skc skd skk skr sks sr- sra srb src srd srk srr srs ss- ssa ssb ssc ssd ssk ssr sss