function  changeLang(flang,tlang)
{
  var url = window.location.href;
  url = url.replace('#','');
  if(window.location.pathname.indexOf('html') <0)
  {
    url = url +'index.html';
  };

  if(url.indexOf('index') <0 ) 
  {
   var newurl = url.replace('_'+flang,'_'+tlang);
   goto(newurl);
  }
  else
  {
   if(flang == 'en')
   {
     var newurl = url.replace('_'+tlang,'').replace('index','index_'+tlang);
     goto(newurl);
   }
   else
   {
      var newurl = url.replace('index_'+flang,'index');
      goto(newurl);
   }
  }

};


function goto(url)
{
  window.location.href=url;
}