function init () {
	rand = Math.ceil(Math.random()*6);
	if (rand>3) {rand=1;}
	document.getElementById("head").style.background = "url(img/head_b"+rand+".png) top left";
}

if (window.addEventListener)
window.addEventListener("load", init, false)
else if (window.attachEvent)
window.attachEvent("onload", init)
else if (document.getElementById)
window.onload=init()