function prefnext(perintah){
	var i;
	if (perintah=1){
		i = document.getElementById('annpos').value - 1;
		if (i == 0 ){i = document.getElementById('jannounce').value;}
	}else{
		i = document.getElementById('annpos').value + 1;
		if (i > document.getElementById('jannounce').value){i=1;}
	}
	document.getElementById('rannc').innerHTML = document.getElementById('hidann' + i).value;
	document.getElementById('annpos').value = i;
}