function change(image1,image2){
	document.images[image1].src="images/"+image2+".jpg";}
function init()
{
button1=new Image;
button2=new Image;
button3=new Image;
button4=new Image;
button1.src="images/over_01.jpg";
button2.src="images/over_02.jpg";
button3.src="images/over_03.jpg";
button4.src="images/over_04.jpg";
}