function changeImage (divButton) {
	var imageUrl = document.getElementById("gamImage").src;
	var TempIndex = imageUrl.lastIndexOf("/");
	imageUrl = imageUrl.substring(TempIndex+1,imageUrl.length);
	var imageName = imageUrl.split("_");
	var imageId = imageName[1].split(".");
	var cont;
	
	if (divButton == "next") {
		cont = parseInt(imageId) + 1;
	}
	else {
		cont = parseInt(imageId) - 1;
	}
	
	if (cont < 28 && cont >= 0) {
		document.getElementById("gamImage").src = "../images/gam/Gam_" + cont + ".JPG" ;
		document.getElementById("counter").innerHTML = cont + 1 + " de 28";
	}

}