a-a aaa aaf aam aao aas af- afa aff afm afo afs ama amf amm amo ams aoa aof aom aoo aos as- asa asf asm aso ass faa faf fam fao fas ffa fff ffm ffo ffs fma fmf fmm fmo fms foa fof fom foo fos fsa fsf fsm fso fss m-f m-o maa maf mam mao mas mfa mff mfm mfo mfs mma mmf mmm mmo mms moa mof mom moo mos msa msf msm mso mss oaa oaf oam oao oas of- ofa off ofm ofo ofs om- oma omf omm omo oms oo- ooa oof oom ooo oos os- osa osf osm oso oss saa saf sam sao sas sfa sff sfm sfo sfs sma smf smm smo sms soa sof som soo sos ss- ssa ssf ssm sso sss