var nbimage= 30;
var width;
var height;
var url;
var alte;
function banniere()
{
numimage= Math.round(Math.random()*(nbimage-1)+1);
if (numimage <= 10)
{
gotosite = "";
url = "images/img_1.gif";
alte = "";
}
if (numimage > 10 && numimage <= 20)
{
gotosite = "";
url = "images/img_2.gif";
alte = "";
}
if (numimage > 20)
{
gotosite = "";
url = "images/img_3.gif";
alte = "";
}
if(gotosite != "")
	{
	document.write ('<A HREF="' + gotosite + '">');	
	}
document.write('<IMG SRC="' + url + '" ALT="' + alte + '" BORDER=0>')
if(gotosite != "")
	{
	document.write('</A>')
	}
}