iii iio iis iit iix io- ioi ioo ios iot is- isi iso iss ist isy iti ito its itt itx ity ixi ixy iyo iys iyt iyy o-i oii oio ois oit oo- ooi ooo oos oot oox os- osi oso oss ost osx ot- oti oto ots ott ox- oxi oxo oxt oxx oxy oyi oyo oys sii sio sis sit six soi soo sos sot sox soy ss- ssi sso sss sst ssx sti sto sts stt stx sty sxi sxs sxt sy- syi sys syt syx t-x tii tio tis tit tix tiy to- toi too tos tot tox toy tsi tso tss tst tsx tsy tti tto tts ttt ttx tty txi txs txt tyo tys tyt xii xio xis xit xix xoi xoo xos xot xox xsi xss xst xti xts xtx xty xxi xxo xxx xxy xyy yii yio yis yit yoi yoo yos yot yox yoy ysi yso yss yst ysy yto yts ytt yxy yys yyt yyy