function hiddenArrow(){
   
 var arrows = 4;
 for(i=1;i<=arrows;i++){
  document.getElementById("arrow"+i).style.visibility = "hidden";
 }
   	
}
   
function changeInfo(id, site1, site2, data){
  
 hiddenArrow();
 document.getElementById("arrow"+id).style.visibility = "visible";
 document.getElementById("site").innerHTML = "<a href='"+site1+"'>"+site2+"</a>"
 document.getElementById("data").innerHTML = data;
   	
}