a-a aaa aaf aag aan aar af- afa aff afg afn afr ag- aga agf agg agn agr an- ana anf ang ann anr ar- ara arf arg arn arr faa faf fag fan far ffa fff ffg ffn ffr fga fgf fgg fgn fgr fna fnf fng fnn fnr fra frf frg frn frr gaa gaf gag gan gar gfa gff gfr gga ggg ggn ggr gna gnf gnn gnr gra grf grg grn grr naa naf nag nan nar nfa nff nfn nfr nga ngf ngg ngn nna nnf nng nnn nra nrf nrg nrn nrr ra- raa raf rag ran rar rfa rff rfg rfn rfr rga rgf rgg rgn rgr rna rng rnn rnr rra rrf rrg rrn rrr