oo- ooo oor oos oot oox or- oro orr ors ort oru orx os- oso osr oss ost osu osx ot- oto otr ots ott otu ou- ouo our ous out ox- oxo oxt oxx roo ror ros rot rou rox rrr rrs rrt rru rso rsr rss rst rsu rsx rto rtr rts rtt rtu rtx ruo rur rus rut ruu rux rxr rxs soo sor sos sot sou sox sr- sro srr srs srt srx ss- sso ssr sss sst ssu ssx sto str sts stt stu stx suo sur sus sut suu sux sxs sxt sxu t-x to- too tor tos tot tou tox tro trr trs trt tru trx tso tsr tss tst tsu tsx tto ttr tts ttt ttu ttx tuo tur tus tut tuu tux txs txt txu uoo uor uos uot uox ur- uro urr urs urt uru urx uso usr uss ust usu usx uto utr uts utt utu utx uur uus uut uuu uxo uxr uxt uxu xoo xor xos xot xox xrt xrx xss xst xtr xts xtx xus xxo xxx