iii iio iip iis iix io- ioi ioo iop ios ipi ipo ipp ips ipx ipy is- isi iso isp iss isy ixi ixy iyo iys iyy o-i oii oio oip ois oo- ooi ooo oop oos oox op- opi opo opp ops opx opy os- osi oso osp oss osx ox- oxi oxo oxx oxy oyi oyo oys p-p pii pio pip pis pix poi poo pop pos pox poy ppi ppo ppp pps ppx ps- psi pso psp pss psx psy pxs py- pyo pys pyx sii sio sip sis six soi soo sop sos sox soy spi spo spp sps spx spy ss- ssi sso ssp sss ssx sxi sxs sy- syi syp sys syx xii xio xis xix xoi xoo xop xos xox xpo xpp xps xsi xsp xss xxi xxo xxp xxx xxy xyp xyy yii yio yip yis yoi yoo yop yos yox yoy ypo yps ysi yso ysp yss ysy yxy yys yyy