rdo rdr rds rdt re- rea rec red ree rei rek rel reo rer res ret ria ric rid rie rii rik ril rio rir ris rit rkc rke rkk rko rks rkt rla rlc rld rle rli rll rlo rlr rls rlt roa roc rod roe roi rok rol roo ror ros rot rra rrc rrd rri rrk rrl rrr rrs rrt rsa rsc rsd rse rsi rsk rsl rso rsr rss rst rta rtc rtd rte rti rtk rtl rto rtr rts rtt saa sac sad sae sai sak sal sao sar sas sat sca scc scd sce sci sck scl sco scr scs sct sda sdc sdd sde sdi sdk sdl sdo sdr sds sdt se- sea sec sed see sei sek sel seo ser ses set sia sic sid sie sii sik sil sio sir sis sit sk- ska skc skd ske ski skk skl sko skr sks skt sla slc sld sle sli slk sll slo slr sls slt soa soc sod soe soi sok sol soo sor sos sot sr- sra src srd sre sri srk srl sro srr srs srt ss- ssa ssc ssd sse ssi ssk ssl sso ssr sss sst sta stc std ste sti stk stl sto str sts stt taa tac tad tae tai tak tal tao tar tas tat tca tcc tcd tce tci tck tcl tco tcr tcs tct tda tdc tdd tde tdi tdk tdl tdo tdr tds tdt te- tea tec ted tee tei tek tel teo ter tes tet tia tic tid tie tii tik til tio tir tis tit tka tkc tke tkk tkl tko tkr tks tkt tla tlc tld tle tli tlk tll tlo tlr tls tlt to- toa toc tod toe toi tok tol too tor tos tot tra trc trd tre tri trk trl tro trr trs trt tsa tsc tsd tse tsi tsk tsl tso tsr tss tst tta ttc ttd tte tti ttk ttl tto ttr tts ttt