a-a a-b aaa aab aap aar aay ab- aba abb abp abr aby ap- apa apb app apr apy ar- ara arb arp arr ary ay- aya ayp ayr b-p baa bab bap bar bay bba bbb bbp bbr bby bpa bpb bpp bpr bpy bra brb brp brr bry by- bya byp byr p-p paa pab pap par pay pba pbb pbp pbr pby ppa ppb ppp ppr pra prb prp prr pry py- pya pyb pyr ra- raa rab rap rar ray rba rbb rbp rbr rpa rpb rpp rpr rra rrb rrp rrr ry- rya ryr ryy yaa yab yap yar yay ybp ybr yby ypa yra yrp yyb yyy