a-a a-b a-c aaa aab aac aad aae aaf aak aas ab- aba abb abc abd abe abf abk abs ac- aca acb acc acd ace acf ack acs ad- ada adb adc add ade adf adk ads aea aeb aec aed aee aef aek aes af- afa afb afc afd afe aff afk afs aka akb akc akd ake akk aks as- asa asb asc asd ase asf ask ass baa bab bac bad bae baf bak bas bba bbb bbc bbd bbe bbf bbk bbs bca bcb bcc bcd bce bcf bck bcs bda bdb bdc bdd bde bdf bdk bds be- bea beb bec bed bee bef bek bes bfa bfb bfc bfd bfe bff bfs bka bkb bkc bke bkf bkk bks bsa bsb bsc bsd bse bsf bsk bss c-- caa cab cac cad cae caf cak cas cba cbb cbc cbd cbe cbf cbk cbs cca ccb ccc ccd cce ccf cck ccs cda cdb cdc cdd cde cdf cdk cds ce- cea ceb cec ced cee cef cek ces cfa cfb cfc cfd cfe cff cfk cfs cka ckb ckc ckd cks csa csb csc csd cse csf csk css daa dab dac dad dae daf dak das dba dbb dbc dbd dbe dbf dbk dbs dca dcb dcc dcd dce dcf dck dcs dda ddb ddc ddd dde ddf ddk dds de- dea deb dec ded dee def dek des dfa dfb dfc dfd dfe dff dfk dfs dka dkb dkc dke dkk dks dsa dsb dsc dsd dse dsf dsk dss eaa eab eac ead eae eaf eak eas eba ebb ebc ebd ebe ebf ebk ebs ec- eca ecb ecc ecd ece ecf eck ecs ed- eda edb edc edd ede edf edk eds eea eeb eec eed eee eef eek ees ef- efa efb efc efd efe eff efs eka ekb ekc ekd eke ekf eks es- esa esb esc esd ese esf esk ess faa fab fac fad fae faf fak fas fba fbb fbc fbd fbe fbf fbk fbs fca fcb fcc fcd fce fcf fck fcs fda fdb fdc fdd fde fdf fdk fds fea feb fec fed fee fef fek fes ffa ffc ffd ffe fff ffk ffs fka fkb fkc fkf fkk fsa fsb fsc fsd fse fsf fsk fss ka- kaa kab kac kad kae kaf kak kas kba kbb kbc kbd kbe kbf kbk kbs kca kcb kcc kcd kce kck kcs kda kdb kdc kde kdf kdk kds ke- kea keb kec ked kee kef kek kes kfa kfc kfd kff kfs kkb kkc kke kkk kks ksa ksb ksc ksd kse ksf ksk kss saa sab sac sad sae saf sak sas sba sbb sbc sbd sbe sbf sbk sbs sca scb scc scd sce scf sck scs sda sdb sdc sdd sde sdf sdk sds se- sea seb sec sed see sef sek ses sfa sfb sfc sfd sfe sff sfk sfs sk- ska skb skc skd ske skf skk sks ss- ssa ssb ssc ssd sse ssf ssk sss