var image_dir = "images/";
var ImageNum = 0;
var TotalNum = 0;

imageArray = new Array();
imageArray[ImageNum++] = image_dir + "gbeberino_1.jpg";
imageArray[ImageNum++] = image_dir + "gbeberino_2.jpg";
imageArray[ImageNum++] = image_dir + "gbeberino_3.jpg";
imageArray[ImageNum++] = image_dir + "gbeberino_4.jpg";
imageArray[ImageNum++] = image_dir + "gbeberino_5.jpg";
imageArray[ImageNum++] = image_dir + "gbeberino_6.jpg";
imageArray[ImageNum++] = image_dir + "gbeberino_7.jpg";
imageArray[ImageNum++] = image_dir + "gbeberino_8.jpg";
imageArray[ImageNum++] = image_dir + "gbeberino_9.jpg";
imageArray[ImageNum++] = image_dir + "gbeberino_10.jpg";
imageArray[ImageNum++] = image_dir + "gbeberino_11.jpg";
imageArray[ImageNum++] = image_dir + "gbeberino_12.jpg";
imageArray[ImageNum++] = image_dir + "gbeberino_13.jpg";
imageArray[ImageNum++] = image_dir + "gbeberino_14.jpg";
imageArray[ImageNum++] = image_dir + "gbeberino_15.jpg";
imageArray[ImageNum++] = image_dir + "gbeberino_16.jpg";

TotalNum = ImageNum;
ImageNum = -1;

function AvanzaImage()
{
   ImageNum++;
   if (ImageNum == TotalNum)
     ImageNum=0;
   document.mainimage.src = imageArray[ImageNum];
}

function RetrocedeImage()
{
   ImageNum--;
   if (ImageNum == -1)
     ImageNum= TotalNum - 1;
   document.mainimage.src = imageArray[ImageNum];
}