iii iio iis iit iix io- ioi ioo ios iot is- isi iso iss ist iti ito its itt itx ixi 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 sii sio sis sit six soi soo sos sot sox ss- ssi sso sss sst ssx sti sto sts stt stx sxi sxs sxt t-x tii tio tis tit tix to- toi too tos tot tox tsi tso tss tst tsx tti tto tts ttt ttx txi txs txt xii xio xis xit xix xoi xoo xos xot xox xsi xss xst xti xts xtx xxi xxo xxx