function rand ( n )
{
  return ( Math.floor ( Math.random ( ) * n + 1 ) );
}
var random_images1 = new Array ( );
random_images1[0] = "FILES/box_1/1.jpg";
random_images1[1] = "FILES/box_1/2.jpg";
random_images1[2] = "FILES/box_1/3.jpg";

var random_images2 = new Array ( );
random_images2[0] = "FILES/box_2/1.jpg";
random_images2[1] = "FILES/box_2/2.jpg";
random_images2[2] = "FILES/box_2/3.jpg";


var random_images3 = new Array ( );
random_images3[0] = "FILES/box_3/1.jpg";
random_images3[1] = "FILES/box_3/2.jpg";
random_images3[2] = "FILES/box_3/3.jpg";

var random_images4 = new Array ( );
random_images4[0] = "FILES/box_4/1.jpg";
random_images4[1] = "FILES/box_4/2.jpg";
random_images4[2] = "FILES/box_4/3.jpg";

 
function pick_image ( )
{
  document.getElementById("random-image1").src = random_images1[rand(3)-1];
   document.getElementById("random-image2").src = random_images2[rand(3)-1];
    document.getElementById("random-image3").src = random_images3[rand(3)-1];
	 document.getElementById("random-image4").src = random_images4[rand(3)-1];
}