a-a a-b aaa aab aaf aao aap aar aay ab- aba abb abf abo abp abr aby af- afa afb aff afo afp afr afy aoa aob aof aoo aop aor ap- apa apb apf apo app apr apy ar- ara arb arf aro arp arr ary ay- aya ayf ayo ayp ayr b-p baa bab baf bao bap bar bay bba bbb bbf bbo bbp bbr bby bfa bfb bff bfo bfp bfr bfy boa bob bof boo bop bor boy bpa bpb bpf bpo bpp bpr bpy bra brb brf bro brp brr bry by- bya byf byo byp byr faa fab faf fao fap far fay fba fbb fbf fbo fbp fbr ffa fff ffo ffp ffr ffy foa fob fof foo fop for foy fpa fpb fpo fpp fpr fpy fra frb frf fro frp frr fry fy- fya fyb fyo fyp oaa oab oaf oao oap oar ob- oba obb obf obo obp obr oby of- ofa ofb off ofo ofp ofr oo- ooa oob oof ooo oop oor op- opa opb opf opo opp opr opy or- ora orb orf oro orp orr ory oya oyo p-p paa pab paf pao pap par pay pba pbb pbf pbo pbp pbr pby pfa pfb pff pfo pfp pfr pfy poa pob pof poo pop por poy ppa ppb ppf ppo ppp ppr pra prb prf pro prp prr pry py- pya pyb pyf pyo pyr ra- raa rab raf rao rap rar ray rba rbb rbf rbo rbp rbr rfa rfb rff rfo rfp rfr roa rob rof roo rop ror roy rpa rpb rpf rpo rpp rpr rra rrb rrf rrp rrr ry- rya ryf ryo ryr ryy yaa yab yaf yao yap yar yay ybf ybp ybr yby yfa yff yfr yob yof yoo yop yor yoy ypa ypf ypo yra yrf yro yrp yyb yyf yyy