a-a a-b a-i aaa aab aaf aai aas aay ab- aba abb abf abi abs aby af- afa afb aff afi afs afy ai- aia aib aif aii ais aiy as- asa asb asf asi ass asy ay- aya ayf ayi ays baa bab baf bai bas bay bba bbb bbf bbi bbs bby bfa bfb bff bfi bfs bfy bi- bia bib bif bii bis biy bsa bsb bsf bsi bss bsy by- bya byf byi bys faa fab faf fai fas fay fba fbb fbf fbi fbs ffa fff ffi ffs ffy fia fib fif fii fis fsa fsb fsf fsi fss fy- fya fyb fyi i-f ia- iaa iab iaf iai ias iba ibb ibf ibi ibs iby ifa ifb iff ifi ifs ify iia iib iif iii iis is- isa isb isf isi iss isy iya iys iyy saa sab saf sai sas say sba sbb sbf sbi sbs sby sfa sfb sff sfi sfs sia sib sif sii sis ss- ssa ssb ssf ssi sss sy- sya syb syi sys yaa yab yaf yai yas yay ybf ybi ybs yby yfa yff yfs yif yii yis ysa ysb ysi yss ysy yyb yyf yys yyy