a = new Array()
var swap_div

var cnt = 4

function get_random(ceiling)
{
	return Math.floor(Math.random()*ceiling)
}

function get_unused_random(which)
{
	while (true)
	{
		rand = get_random(cnt)
		var i = 0
		for (i = 0; i < which; i++)
		{
			if (a[i] == rand)
				break;
		}
		if (i == which)
		{
			a[which] = rand
			return
		}
	}
}

function shuffle()
{

	var ad0 = document.getElementById("ad0")
	var ad1 = document.getElementById("ad1")
	var ad2 = document.getElementById("ad2")
	var ad3 = document.getElementById("ad3")

	ad0.style.display = "none"
	ad1.style.display = "none"
	ad2.style.display = "none"
	ad3.style.display = "none"

	a[0] = get_random(cnt)
	a[1] = -1
	a[2] = -1
	a[3] = -1

	get_unused_random(1)
	get_unused_random(2)
	get_unused_random(3)

	ad0 = document.getElementById("ad0")
	ad1 = document.getElementById("ad1")
	ad2 = document.getElementById("ad2")
	ad3 = document.getElementById("ad3")

	var swap0 = document.getElementById("swap0")
	var swap1 = document.getElementById("swap1")
	var swap2 = document.getElementById("swap2")
	var swap3 = document.getElementById("swap3")

	swap0.innerHTML = ad0.innerHTML
	swap1.innerHTML = ad1.innerHTML
	swap2.innerHTML = ad2.innerHTML
	swap3.innerHTML = ad3.innerHTML

	ad0.innerHTML = document.getElementById("swap" + a[0]).innerHTML
	ad1.innerHTML = document.getElementById("swap" + a[1]).innerHTML
	ad2.innerHTML = document.getElementById("swap" + a[2]).innerHTML
	ad3.innerHTML = document.getElementById("swap" + a[3]).innerHTML

	ad0.style.display = "block"
	ad1.style.display = "block"
	ad2.style.display = "block"
	ad3.style.display = "block"

}