var last="";
var rot13map;
function rot13init()

{
  var map = new Array();
  var s   = "abcdefghijklmnopqrstuvwxyz";
  
  for (i=0; i<s.length; i++)
    map[s.charAt(i)]			= s.charAt((i+13)%26);
  for (i=0; i<s.length; i++)
    map[s.charAt(i).toUpperCase()]	= s.charAt((i+13)%26).toUpperCase();
  return map;
}
 
function rot13(a)
{
  if (!rot13map)
    rot13map=rot13init();
  s = "";
  for (i=0; i<a.length; i++)
    {
      var b = a.charAt(i);
 
      s	+= (b>='A' && b<='Z' || b>='a' && b<='z' ? rot13map[b] : b);
    }
  return s;
}
 
function upd()
{
  if (document.forms[0].text.value==last)
    return;
 
  last = document.forms[0].text.value;
  document.forms[0].rot13.value = rot13(last);
}