serc serd sere serf sern sero serr sers sesc sese seso sess sfcc sfco sfcs sfdc sfer sffc sfne sfor sfos sfrc sfro sfss sncc sncf snco sned snee sner snes snns snoc snod snoo snor snos snrs snsd soce soco socr socs sodd sode sodo sods soec soen soeo soes sofo son- sond sone sono sons sood soof soon soor soos sord sore sorn soro sorr sors sose soso soss srcc srde srec sreo sres srfc srnn srno sros srsd sscc ssce sscs ssdc ssdd ssdf ssec ssee sses ssfc ssns ssoc ssrc ssrs sssc sssf ssss