bbb bbi bbo bbs bi- bib bii bio bis biv bob boi boo bos bov bsb bsi bso bss bsv bvb bvi bvo bvs bvv i-v ibb ibi ibo ibs ibv iib iii iio iis io- iob ioi ioo ios iov is- isb isi iso iss isv ivb ivi ivo ivs ivv o-i ob- obb obi obo obs obv oib oii oio ois oiv oo- oob ooi ooo oos oov os- osb osi oso oss osv ov- ovb ovi ovo ovs ovv sbb sbi sbo sbs sbv sib sii sio sis siv sob soi soo sos sov ss- ssb ssi sso sss ssv svb svi svo svs svv vbi vbo vbs vbv vi- vib vii vio vis viv vob voi voo vos vov vsb vsi vso vss vsv vvb vvi vvo vvs vvv