var slideshowCounts = {};
var initSlideshow = function(prefix) {
	var el;
	slideshowCounts[prefix] = 0;
	for ( var i = 0; i <= 20; i++ ) {
		el = did(prefix + '_' + i);
		if ( el ) {
			slideshowCounts[prefix] = i;
		} else {
			break;
		}
	}
	cycleImages(prefix, 0);
};


var cycleImages = function(id_prefix, counter) {
	counter = counter || 0;
	var count = slideshowCounts[id_prefix];
	var el;

	for ( var i = 0; i <= count; i++ ) {
		el = did(id_prefix + '_' + i);
		el.style.display = (i == counter) ? '' : 'none';
	}

	counter++;
	if ( counter > count ) {
		counter = 0;
	}

	setTimeout(function() { cycleImages(id_prefix, counter); }, 3000);
};