var a=Math.random()*6;
var b=Math.round(a);

var img = "iso_icons/imgleft_01.gif";
if ( ( b < 1 ) || ( b > 6 ) )
{ 
document.getElementById('img_left').src=img; 
}
else
{
img = "iso_icons/imgleft_0" + b + ".gif";
document.getElementById('img_left').src = img;
}
	
//alert(img);