jQuery.easing.easeOutQuart = function (x, t, b, c, d) {
	return -c * ((t=t/d-1)*t*t*t - 1) + b;
};

jQuery(function( $ ){
	var totalItens = $("#slideshow li").length;
	$('.prev.setas').hide();
	if (totalItens > 4)
		$('.next.setas').show();
	$('#slideshow').serialScroll({
		items:'li',
		prev:'a.prev',
		next:'a.next',
		start:0,
		duration:1200,
		force:true,
		stop:true,
		lock:false,
		cycle:false,
		easing:'easeOutQuart',
		jump: false,
		step:1,
		onBefore: function(ele, ele2, ele3, items, pos) {
			if (pos <= 0)
				$('.prev.setas').hide();
			else
				$('.prev.setas').show();
			if (pos >= items.length - 3)
				$('.next.setas').hide();
			else
				$('.next.setas').show();
			
			return pos < items.length - 3;
		}
	});

});