function startUp()
{
   if(document.getElementById("aimages") && document.getElementById("hiddenimages"))
   {
     var pictures = document.getElementById("hiddenimages").getElementsByTagName("span");
     
     var imageLink = document.getElementById("imagelink"); 
     var mainImage = document.getElementById("mainimage");

       for (var i=0; i< pictures.length; i++)
       {
         pictures[i].pic = i;
       }
       mainImage.src = pictures[0].innerHTML;
       mainImage.pic = 0;
       
       var re_FindMedIndicator = /_med[.]/;
       imageLink.href = pictures[0].innerHTML.replace(re_FindMedIndicator, '.');
     if(pictures.length > 1)
     { 
       var leftArrow = document.getElementById("backarrow");
       leftArrow.onclick = leftClick;
       var rightArrow = document.getElementById("forwardarrow");
       rightArrow.onclick = rightClick;
    }
   }

}

function rightClick()
{
   var re_FindMedIndicator = /_med[.]/; 
   var mainImage = document.getElementById("mainimage");
   var imageLink = document.getElementById("imagelink");
   var imageNumber = document.getElementById("imagenumber");
       
   var pictures = document.getElementById("hiddenimages").getElementsByTagName("span");
   for (var i=0; i< pictures.length; i++)
   {
      if (mainImage.pic == pictures[i].pic)
      {
          if(i+1 < pictures.length)
          {
           mainImage.src = pictures[i+1].innerHTML;
           mainImage.pic = i+1;
           imageLink.href = pictures[i+1].innerHTML.replace(re_FindMedIndicator, '.');
           imageNumber.innerHTML = i+2;
          }
          else
          {
            leftClick();            
          }
          break;          
      }
   }
}

function leftClick()
{
   var re_FindMedIndicator = /_med[.]/;
   var mainImage = document.getElementById("mainimage");
   var imageLink = document.getElementById("imagelink");  
   var imageNumber = document.getElementById("imagenumber");
   var pictures = document.getElementById("hiddenimages").getElementsByTagName("span");

   for (var i=0; i< pictures.length; i++)
   {

      if (mainImage.pic == pictures[i].pic)
      {
         
          if((i-1) >= 0)
          {
           mainImage.src = pictures[i-1].innerHTML;
           mainImage.pic = i-1;
           imageLink.href = pictures[i-1].innerHTML.replace(re_FindMedIndicator, '.');
           imageNumber.innerHTML = i;
          }
          else
          {
            rightClick();
          }
          break;          
      }
   }

}