bbb bbf bbi bbo bbs bfb bff bfi bfo bfs bi- bib bif bii bio bis bob bof boi boo bos bsb bsf bsi bso bss fbb fbf fbi fbo fbs fff ffi ffo ffs fib fif fii fis fob fof foi foo fos fsb fsf fsi fso fss i-f ibb ibf ibi ibo ibs ifb iff ifi ifo ifs iib iif iii iio iis io- iob iof ioi ioo ios is- isb isf isi iso iss o-i ob- obb obf obi obo obs of- ofb off ofi ofo ofs oib oif oii oio ois oo- oob oof ooi ooo oos os- osb osf osi oso oss sbb sbf sbi sbo sbs sfb sff sfi sfo sfs sib sif sii sio sis sob sof soi soo sos ss- ssb ssf ssi sso sss