bbb bbf bbo bbs bbt bby bfb bff bfo bfs bft bfy bob bof boo bos bot boy bsb bsf bso bss bst bsy btb btf bto bts btt bty by- byf byo bys byt fbb fbf fbo fbs fbt fff ffo ffs fft ffy fob fof foo fos fot foy fsb fsf fso fss fst ftb ftf fto fts ftt fty fy- fyb fyo ob- obb obf obo obs obt oby of- ofb off ofo ofs oft oo- oob oof ooo oos oot os- osb osf oso oss ost ot- otb otf oto ots ott oyo oys sbb sbf sbo sbs sbt sby sfb sff sfo sfs sft sob sof soo sos sot soy ss- ssb ssf sso sss sst stb stf sto sts stt sty sy- syb sys syt tbb tbf tbo tbs tbt tfb tff tfo tfs tft to- tob tof too tos tot toy tsb tsf tso tss tst tsy ttb ttf tto tts ttt tty tyf tyo tys tyt ybf ybs yby yff yfs yft yob yof yoo yos yot yoy ysb yso yss yst ysy ytf yto yts ytt yyb yyf yys yyt yyy