-er a-a a-b a-c aaa aab aac aad aae aak aar aas ab- aba abb abc abd abe abk abr abs ac- aca acb acc acd ace ack acr acs ad- ada adb adc add ade adk adr ads aea aeb aec aed aee aek aer aes aka akb akc akd ake akk akr aks ar- ara arb arc ard are ark arr ars as- asa asb asc asd ase ask asr ass baa bab bac bad bae bak bar bas bba bbb bbc bbd bbe bbk bbr bbs bca bcb bcc bcd bce bck bcr bcs bda bdb bdc bdd bde bdk bdr bds be- bea beb bec bed bee bek ber bes bka bkb bkc bke bkk bkr bks bra brb brd bre brk brr brs bsa bsb bsc bsd bse bsk bsr bss c-- caa cab cac cad cae cak car cas cba cbb cbc cbd cbe cbk cbr cbs cca ccb ccc ccd cce cck ccr ccs cda cdb cdc cdd cde cdk cdr cds ce- cea ceb cec ced cee cek cer ces cka ckb ckc ckd cks cra crb crc crd cre crk crr crs csa csb csc csd cse csk csr css daa dab dac dad dae dak dar das dba dbb dbc dbd dbe dbk dbr dbs dca dcb dcc dcd dce dck dcr dcs dda ddb ddc ddd dde ddk ddr dds de- dea deb dec ded dee dek der des dka dkb dkc dke dkk dkr dks dra drb drc drd dre drk drr drs dsa dsb dsc dsd dse dsk dsr dss eaa eab eac ead eae eak ear eas eba ebb ebc ebd ebe ebk ebr ebs ec- eca ecb ecc ecd ece eck ecr ecs ed- eda edb edc edd ede edk edr eds eea eeb eec eed eee eek eer ees eka ekb ekc ekd eke ekr eks era erb erc erd ere erk err ers es- esa esb esc esd ese esk esr ess ka- kaa kab kac kad kae kak kar kas kba kbb kbc kbd kbe kbk kbr kbs kca kcb kcc kcd kce kck kcr kcs kda kdb kdc kde kdk kdr kds ke- kea keb kec ked kee kek ker kes kkb kkc kke kkk kkr kks kra krc krd krk krr krs ksa ksb ksc ksd kse ksk ksr kss ra- raa rab rac rad rae rak rar ras rba rbb rbc rbd rbe rbk rbr rbs rca rcb rcc rcd rce rcr rcs rda rdb rdc rdd rde rdr rds re- rea reb rec red ree rek rer res rkb rkc rke rkk rks rra rrb rrc rrd rrk rrr rrs rsa rsb rsc rsd rse rsk rsr rss saa sab sac sad sae sak sar sas sba sbb sbc sbd sbe sbk sbr sbs sca scb scc scd sce sck scr scs sda sdb sdc sdd sde sdk sdr sds se- sea seb sec sed see sek ser ses sk- ska skb skc skd ske skk skr sks sr- sra srb src srd sre srk srr srs ss- ssa ssb ssc ssd sse ssk ssr sss