function setcookie(cookname,cookvalue,expiredt)
{
  document.cookie=cookname+"="+cookvalue+"; expires="+expiredt+"; path=/;";
}

function delcookie(cookiename)
{
  document.cookie=cookiename+"=bb; expires=Saturday, 16-Sep-90 23:59:59 GMT; path=/"+"";
}

function getcookie(name)
{
  var dc = document.cookie;
  var prefix = name + "=";
  var begin = dc.indexOf("; " + prefix);
  if (begin == -1) {
    begin = dc.indexOf(prefix);
    if (begin != 0) return null;
  } else
    begin += 2;
  var end = document.cookie.indexOf(";", begin);
  if (end == -1)
    end = dc.length;
  return unescape(dc.substring(begin + prefix.length, end));
}