function switch_img(divName, totalImgs) {
			for (var i=1; i<=totalImgs; i++) {
				var showDivName = 'photo_' + i;
				var showObj = document.getElementById(showDivName);
				if (showDivName == divName)
					showObj.style.display = 'block';
				else
					showObj.style.display = 'none';
				}
			}