b-u bbb bbc bbd bbo bbs bbu bcb bcc bcd bco bcs bcu bdb bdc bdd bdo bds bdu bob boc bod boo bos bou bsb bsc bsd bso bss bsu bub buc bud buo bus buu c-- cbb cbc cbd cbo cbs cbu ccb ccc ccd cco ccs ccu cdb cdc cdd cdo cds cdu co- cob coc cod coo cos cou csb csc csd cso css csu cub cuc cud cuo cus cuu dbb dbc dbd dbo dbs dbu dcb dcc dcd dco dcs dcu ddb ddc ddd ddo dds ddu dob doc dod doo dos dou dsb dsc dsd dso dss dsu dub duc dud duo dus ob- obb obc obd obo obs obu oc- ocb occ ocd oco ocs ocu odb odc odd odo ods odu oo- oob ooc ood ooo oos os- osb osc osd oso oss osu ou- ouc oud ouo ous sbb sbc sbd sbo sbs sbu scb scc scd sco scs scu sdb sdc sdd sdo sds sdu sob soc sod soo sos sou ss- ssb ssc ssd sso sss ssu sub suc sud suo sus suu ubb ubc ubo ubs ubu ucb ucc ucd uco ucs ucu udb udc udd udo uds udu uob uoc uod uoo uos usb usc usd uso uss usu uuc uus uuu