var ssElem = 0;
var ssCurSlide = 1;

function setupSlideshow()
{
	var x = 1;
	// increment until slideshow_x is null
	while (document.getElementById("ss_" + x))
		x++;
	// x is one too many, subtract one
	x--;
	ssElem = x;
	for (var i=2; i<(x+1); i++)
	{
		document.getElementById("ss_" + i).style.display = "none";
	}
}

function nextSlide()
{
	document.getElementById("ss_" + ssCurSlide).style.display = "none";
	ssCurSlide = (ssCurSlide % ssElem) + 1;
	document.getElementById("ss_" + ssCurSlide).style.display = "block";
}

function prevSlide()
{
	document.getElementById("ss_" + ssCurSlide).style.display = "none";
	ssCurSlide = (((ssCurSlide + ssElem) - 2) % ssElem) + 1;
	document.getElementById("ss_" + ssCurSlide).style.display = "block";
}

addLoadEvent (setupSlideshow);