my_pics=new Array();

my_pics[0]='img/index/main_image_1.jpg';
my_pics[1]='img/index/main_image_2.jpg';
my_pics[2]='img/index/main_image_3.jpg';
my_pics[3]='img/index/main_image_4.jpg';

function pict()

	{
	a=Math.floor(Math.random()*my_pics.length);
	document.images["mypic"].src=my_pics[a];
	}