function random_image(num1,num2) {
if((num1 - num2) > 0) {
var big = num1
var small = num2
} else {
var big = num2
var small = num1
}
var range = big - small + 1
var number = Math.floor(Math.random()*range) + small
return(number)
}

function random_img() {
var img_src = "http://www.s-cube-a.com/wp/wp-content/changeimage/" + random_image(1,6) + ".jpg"
document.write("<IMG SRC='" + img_src + "' width=660 height=240 />")
}