a-a a-b aaa aab aam aan aao aas ab- aba abb abm abn abo abs ama amb amm amn amo ams an- ana anb anm ann ano ans aoa aob aom aon aoo aos as- asa asb asm asn aso ass baa bab bam ban bao bas bba bbb bbm bbn bbo bbs bma bmb bmm bmn bmo bms bna bnb bnn bno bns boa bob bom bon boo bos bsa bsb bsm bsn bso bss m-o maa mab mam man mao mas mba mbb mbm mbo mbs mma mmb mmm mmn mmo mms mna mnb mnm mnn mno mns moa mob mom mon moo mos msa msb msm msn mso mss naa nab nam nan nao nas nba nbb nbm nbn nbo nbs nma nmb nmm nmn nmo nms nna nnb nnm nnn nno nns no- noa nob nom non noo nos nsa nsb nsm nsn nso nss oaa oab oam oan oao oas ob- oba obb obm obn obo obs om- oma omb omm omn omo oms on- ona onb onn ono ons oo- ooa oob oom oon ooo oos os- osa osb osm osn oso oss saa sab sam san sao sas sba sbb sbm sbn sbo sbs sma smb smm smn smo sms sna snb snm snn sno sns soa sob som son soo sos ss- ssa ssb ssm ssn sso sss