var but=new Array(12)
var loaded=false
for(i=0;i<12;i++) but[i]=new Image

function images_preload(){
but[0].src="/images/news.jpg";
but[1].src="/images/about.jpg";
but[2].src="/images/guaranty.jpg";
but[3].src="/images/buy.jpg";
but[4].src="/images/scheme.jpg";
but[5].src="/images/contacts.jpg";

but[6].src="/images/news.gif";
but[7].src="/images/about.gif";
but[8].src="/images/guaranty.gif";
but[9].src="/images/buy.gif";
but[10].src="/images/scheme.gif";
but[11].src="/images/contacts.gif";
loaded=true
}
function Focus (N, S) {on(N,S,1)}
function Blur (N, S) {on(N,S,0)}

function on(N,S,switcher){

button = document.getElementById("but"+N)
if(loaded) {
    button.src=(switcher?(but[N-1].src):(but[N-1+6].src))
    document.getElementById('limg'+N).style.display=switcher?"block":"none";
    document.getElementById('rimg'+N).style.display=switcher?"block":"none";
}

}