function randomize(min, max) {
	if (!min)
		min = 0;
	if (!max)
		max = 1;
	return Math.floor(Math.random()*(max+1)+min);
}
function randomBg() {
	var bgs = new Array();

	bgs.push("../images/bg/01.jpg");
	bgs.push("../images/bg/02.jpg");
	bgs.push("../images/bg/03.jpg");
	bgs.push("../images/bg/04.jpg");
	bgs.push("../images/bg/05.jpg");
	bgs.push("../images/bg/06.jpg");
	bgs.push("../images/bg/07.jpg");
	bgs.push("../images/bg/08.jpg");
	bgs.push("../images/bg/09.jpg");
	bgs.push("../images/bg/10.jpg");
	bgs.push("../images/bg/11.jpg");
	bgs.push("../images/bg/12.jpg");

	document.body.style.backgroundImage = "url(" + bgs[randomize(0, bgs.length-1)] + ")";
}