function change_to(item, to) {
	item.src = item.src.split("_")[0] + "_" + to + ".gif";
}

function rotate_image() {
	current_image = (current_image == image_num) ? 1 : (current_image + 1)
	$("top_referenciak").src = "images/top_referenciak_" + current_image + ".gif";
}
var image_num = 4;
var current_image = 1;

new PeriodicalExecuter(rotate_image, 4);