var img = 0;
var imgHeight = 0;
var clickableCount = 0;

$(document).ready(function(){
	imgHeight = $("#slide li").height();
	displayCount = Math.floor($("#slide").height() / imgHeight);
	clickableCount = $("#slide li").length - displayCount;
	$("#slide").css("overflow","hidden");
	$("#up").click(function(){
		if(img>0){
			img--;
			$("#slide ul").animate({
				marginTop:"-" + (img*imgHeight) + "px"
			})
		}
	})
	$("#down").click(function(){
		if(img<clickableCount){
			img++;
			$("#slide ul").animate({
				marginTop:"-" + (img*imgHeight) + "px"
			})
		}
	})
})