c-- ccc ccd cce ccs cct cdc cdd cde cds cdt ce- cec ced cee ces cet csc csd cse css cst ctc ctd cte cts ctt dcc dcd dce dcs dct ddc ddd dde dds ddt de- dec ded dee des det dsc dsd dse dss dst dtc dtd dte dts dtt ec- ecc ecd ece ecs ect ed- edc edd ede eds edt eec eed eee ees eet es- esc esd ese ess est etc etd ete ets ett scc scd sce scs sct sdc sdd sde sds sdt se- sec sed see ses set ss- ssc ssd sse sss sst stc std ste sts stt tcc tcd tce tcs tct tdc tdd tde tds tdt te- tec ted tee tes tet tsc tsd tse tss tst ttc ttd tte tts ttt