count = 0;
randa = 0;
randb = 0;
randfin = 0;
nrandfin = 0;
Max = 8;

function changeImg() {
	randa =Math.floor(Math.random()*10);
	randb =Math.floor(Math.random()*100);
	randb =Math.floor(randb / 10);
	if(randa >= 5) { randa = 1;} else {randa = 0;}
	if(randb >= 7) { if(randa == 1){randb = Math.floor(randb / 2);};} 
	if(randa == 1) { randfin = randb + 10;} else {if(randb == 0) { randfin = 1;} else{randfin = randb;}}
	if(document.all) {document.images["btn"+randfin].src ="ch_img/"+count+".gif";}
	if(!document.all && document.getElementById) {document.images["btn"+randfin].src ="ch_img/"+count+".gif";}
	if(count >= Max){count =0;}else{count++;}
}

function MM_preloadImages() { //v3.0
  var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
    var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
    if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
}