function doCheck(){
	var file = document.banner.src;
	var banNum = file.substring(file.length - 5, file.length - 4);

	var contentFile = document.content_pic.src;
	var contentNum = contentFile.substring(contentFile.length - 5, contentFile.length - 4);

	alert(banNum + " " + contentNum);

	if (contentNum == banNum){
		if (contentNum <= 6 && contentNum > 1)
			document.content_pic.src = "images/content_pics/content_pic_" + (contentNum - 1) + ".png";
		else
			document.content_pic.src= "images/content_pics/content_pic_" + (contentNum + 1) + ".png";
	}
}