a-a aaa aaf aag aao aap af- afa aff afg afo afp ag- aga agf agg ago agp aoa aof aog aoo aop ap- apa apf apg apo app faa faf fag fao fap ffa fff ffg ffo ffp fga fgf fgg fgp foa fof fog foo fop fpa fpg fpo fpp g-p gaa gaf gag gao gap gfa gff gfo gfp gga ggg ggo ggp goa gof gog goo gop gpa gpf gpg gpo gpp oaa oaf oag oao oap of- ofa off ofg ofo ofp oga ogf ogg ogo ogp oo- ooa oof oog ooo oop op- opa opf opg opo opp p-p paa paf pag pao pap pfa pff pfg pfo pfp pga pgf pgg pgo pgp poa pof pog poo pop ppa ppf ppg ppo ppp