a-a a-b aaa aab aam aan aar ab- aba abb abm abn abr ama amb amm amn amr an- ana anb anm ann anr ar- ara arb arm arn arr baa bab bam ban bar bba bbb bbm bbn bbr bma bmb bmm bmn bmr bna bnb bnn bnr bra brb brm brn brr m-r maa mab mam man mar mba mbb mbm mbr mma mmb mmm mmn mmr mna mnb mnm mnn mnr mra mrb mrm mrn mrr naa nab nam nan nar nba nbb nbm nbn nbr nma nmb nmm nmn nmr nna nnb nnm nnn nra nrb nrm nrn nrr ra- raa rab ram ran rar rba rbb rbm rbn rbr rma rmb rmm rmn rmr rna rnb rnm rnn rnr rra rrb rrm rrn rrr