var the_timeout;
	var key = 0;
	var pre = -1;
	var num = 3;

	function rotateMainbg(){
		for(var i=0;i<num;i++){
			document.getElementById(i+1).src = 'images/mian_img_bt_blue.png';
			//document.getElementById(0).src = 'images/main_bt_stop.png';
			document.getElementById('img'+(i+1)).style.zIndex = -1000;
		}
		if((pre!=-1)&&(pre!=key)) document.getElementById('img'+(pre+1)).style.zIndex = 1500;
		document.getElementById('img'+(key+1)).style.zIndex = 1000;
		document.getElementById(key+1).src = 'images/mian_img_bt_glay.png';
		if((pre!=-1)&&(pre!=key)) $("#img"+(pre+1)).fadeOut(500);
		$("#img"+(key+1)).fadeIn(500);
		pre = key;
		key++;
		if (key >= num){ key = 0; }
		var function_string = "rotateMainbg("+key+");";
		the_timeout = setTimeout(function_string,8000);
	}
	function showImage(index){
		key = index;
		clearTimeout(the_timeout);
		rotateMainbg();
	}
	rotateMainbg();