function RandomNumber(d) {
 return Math.floor((d+1)*Math.random());
}    
function RandomGraphics() {
        document.write("<img id=background_scale src="+x[RandomNumber(x.length-1)]+">");   
    }
function RandomGraphics_header() {
        document.write("<img src="+x[RandomNumber(x.length-1)]+" width=400 height=90>");   
    }