bbb bbi bbo bbs bbt bby bi- bib bii bio bis bit biy bob boi boo bos bot boy bsb bsi bso bss bst bsy btb bti bto bts btt bty by- byi byo bys byt ibb ibi ibo ibs ibt iby iib iii iio iis iit io- iob ioi ioo ios iot is- isb isi iso iss ist isy itb iti ito its itt ity iyo iys iyt iyy o-i ob- obb obi obo obs obt oby oib oii oio ois oit oo- oob ooi ooo oos oot os- osb osi oso oss ost ot- otb oti oto ots ott oyi oyo oys sbb sbi sbo sbs sbt sby sib sii sio sis sit sob soi soo sos sot soy ss- ssb ssi sso sss sst stb sti sto sts stt sty sy- syb syi sys syt tbb tbi tbo tbs tbt tib tii tio tis tit tiy to- tob toi too tos tot toy tsb tsi tso tss tst tsy ttb tti tto tts ttt tty tyo tys tyt ybi ybs yby yii yio yis yit yob yoi yoo yos yot yoy ysb ysi yso yss yst ysy yto yts ytt yyb yys yyt yyy