function show(_index){
		_index = _index > 5? 5:_index;
		var _cnt = document.getElementById('js-ad');
		_cnt.src = 'image/cnt/adset'+_index+'.gif';
		var _btn = document.getElementById('js-btn').getElementsByTagName('a');
		for(var i=0;i<5;i++){
			_btn[i].className = '';
			} 
		_btn[_index].className = 'js-crt';
	}; 
	
	var isround = '',scrollmove = '';	
	function change(_index){
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		clearTimeout(isround);
		clearInterval(scrollmove);
		show(_index);
		if((next = _index + 1)>4){next = 0;}
		isround = setTimeout("change("+next +")",4000); 
	} 
 	window.onload = function(){setTimeout(change,2000);}