var t;
var idx = 1;
var elapsed = 5000;
// var maxidx = 4;

function addLoadEvent(func) {
    var oldonload = window.onload;
    if (typeof window.onload != 'function') {
        window.onload = func;
    } else {
        window.onload = function() {
            if (oldonload) {
                oldonload();
            }
            func();
        }
    }
}

function StartSlide() {
  var sld = document.getElementById("sld1");
  sld.style.display = "block";
  t=setTimeout("NextSlide()",elapsed);
}

function NextSlide() {
  var sld = document.getElementById("sld"+idx);
  sld.style.display = "none";
  idx++;
  if (idx > maxidx) { idx = 1; }
  sld = document.getElementById("sld"+idx);
  sld.style.display = "block";
  t=setTimeout("NextSlide()",elapsed);
}

addLoadEvent(StartSlide);