var speed_head_roll=1;
var speed_head_roll_stop=3000;
var headRollObj = document.getElementById("demo");
var realHeadRollHeight=demo1.offsetHeight;
demo2.innerHTML = demo1.innerHTML;
function headRoll(){
clearInterval(MyMarTop);
var t_s=headRollObj.scrollTop;
if(t_s>=realHeadRollHeight) t_s=0;
t_s++;
headRollObj.scrollTop=t_s;
var isStop=t_s%174;

if(isStop==0)
	{
    	MyMarTop=setInterval(headRoll,speed_head_roll_stop);
		
	}
	else
	{
    	MyMarTop=setInterval(headRoll,speed_head_roll);
	}
}
var MyMarTop=setInterval(headRoll,speed_head_roll_stop);
demo.onmouseover=function() {
clearInterval(MyMarTop)
}
demo.onmouseout=function() {
MyMarTop=setInterval(headRoll,speed_head_roll)
}