a-a a-b a-c aaa aab aac aad aan aao aas ab- aba abb abc abd abn abo abs ac- aca acb acc acd acn aco acs ad- ada adb adc add adn ado ads an- ana anb anc and ann ano ans aoa aob aoc aod aon aoo aos as- asa asb asc asd asn aso ass baa bab bac bad ban bao bas bba bbb bbc bbd bbn bbo bbs bca bcb bcc bcd bcn bco bcs bda bdb bdc bdd bdo bds bna bnb bnc bnd bnn bno bns boa bob boc bod bon boo bos bsa bsb bsc bsd bsn bso bss c-- caa cab cac cad can cao cas cba cbb cbc cbd cbn cbo cbs cca ccb ccc ccd ccn cco ccs cda cdb cdc cdd cdn cdo cds cn- cna cnb cnc cnd cnn cno cns co- coa cob coc cod con coo cos csa csb csc csd csn cso css daa dab dac dad dan dao das dba dbb dbc dbd dbn dbo dbs dca dcb dcc dcd dcn dco dcs dda ddb ddc ddd ddn ddo dds dna dnb dnc dnd dnn dno dns doa dob doc dod don doo dos dsa dsb dsc dsd dsn dso dss naa nab nac nad nan nao nas nba nbb nbc nbd nbn nbo nbs nca ncb ncc ncd ncn nco ncs nda ndb ndc ndd ndn ndo nds nna nnb nnc nnn nno nns no- noa nob noc nod non noo nos nsa nsb nsc nsd nsn nso nss oaa oab oac oad oan oao oas ob- oba obb obc obd obn obo obs oc- oca ocb occ ocd ocn oco ocs oda odb odc odd odn odo ods on- ona onb onc ond onn ono ons oo- ooa oob ooc ood oon ooo oos os- osa osb osc osd osn oso oss saa sab sac sad san sao sas sba sbb sbc sbd sbn sbo sbs sca scb scc scd scn sco scs sda sdb sdc sdd sdn sdo sds sna snb snc snd snn sno sns soa sob soc sod son soo sos ss- ssa ssb ssc ssd ssn sso sss