function swapimg()
{
var strImgname = parent.banner.document.bannerpic.src;
var intImgnum = strImgname.lastIndexOf(".")-1;
var strImgnum = strImgname.charAt(intImgnum);
//alert(strImgname + " -- " + intImgnum + " " + strImgnum);
var strNewImgnum
do {  strNewImgnum = Math.floor(1+Math.random()*4).toString();
		//alert("old=" + strImgnum + " new=" + strNewImgnum);
	} while ( strNewImgnum == strImgnum );
parent.banner.document.bannerpic.src = strImgname.substring(0,intImgnum) 
	+ strNewImgnum + strImgname.substr(intImgnum+1,strImgname.length);
}