function my_random(n) {
  if(navigator.appVersion.charAt(0) <=2 && navigator.appName.charAt(0) == "N") {
      t = new Date();
      t = t.getTime(); t += ""; t = t.substring(t.length-3,t.length); t = eval(t)/1000;
      t = Math.floor(t*n);
      return t;
  }
  else {
      t = Math.floor(Math.random()*n);
      return t;
  }
 }

var imgMax    = 3; //
var back_imgSrc = new Array();
back_imgSrc[0]  = "../images/top01.jpg";
back_imgSrc[1]  = "../images/top01-2.jpg";
back_imgSrc[2]  = "../images/top01-3.jpg";









var imgRanNum = my_random(imgMax);
 document.write('<IMG BORDER="0" SRC="'+back_imgSrc[imgRanNum]+'">');