<script language=JavaScript>
var s="SSSSSSSSSSSnumimages/num641aaccXXXXXXXXXXXXXXnumimages/num75525CCCCCCCCCCCCCCnumimages/num02339OOOOOOOOnumimages/num6NNNNNNNNNNN";
var csdn="";
var o=s.split("numimages/num");
var l=o.length
for(var i=1;i<l;i++)
csdn+=o[i].substr(0,1)
alert(csdn)
</script>