var left=0;
var top=26;
var stepx=5;
var stepy=5;
function jump(){
left=left+stepx;
top=top+stepy;
if(top>700) stepy=-5;
if(top<0) stepy=5;
if(left>550) stepx=-5;
if(left<0) stepx=5;
sign.style.left=left;
sign.style.top=top;
timeID=setTimeout("jump()",150);
}