var randam;
function randomImgL(){
  var imgsL = 5;//左画像の要素の数
  n = Math.floor(Math.random()*imgsL) + 1;
  bannerID = document.getElementById("randomL" + n);
  bannerID.style.display = "block";
}
function randomImgR(){
  var imgsR = 4;//右画像の要素の数
  m = Math.floor(Math.random()*imgsR) + 1;
  bannerIDR = document.getElementById("randomR" + m);
  bannerIDR.style.display = "block";
}
if(window.onload){
  randam = window.onload;
}
window.onload = function(){
  if(randam){
  t.call(null);
  }
  randomImgL();
  randomImgR();
}