function ad_ec()
{
  if (document.getElementById('ad_container').style.width == '751px')
  {
    document.getElementById('ad_container').style.width = '171px';
    document.getElementById('ad_container').style.height = '122px';
  } else {
    document.getElementById('ad_container').style.width = '751px';
    document.getElementById('ad_container').style.height = '431px';
  }
}