a-a a-b aaa aab aap aas aay ab- aba abb abp abs aby ap- apa apb app aps apy as- asa asb asp ass asy ay- aya ayp ays b-p baa bab bap bas bay bba bbb bbp bbs bby bpa bpb bpp bps bpy bsa bsb bsp bss bsy by- bya byp bys p-p paa pab pap pas pay pba pbb pbp pbs pby ppa ppb ppp pps ps- psa psb psp pss psy py- pya pyb pys saa sab sap sas say sba sbb sbp sbs sby spa spb spp sps spy ss- ssa ssb ssp sss sy- sya syb syp sys yaa yab yap yas yay ybp ybs yby ypa yps ysa ysb ysp yss ysy yyb yys yyy