function  changelang() {  

	var str = window.location.href;
	// cerca la stringa 'eng'
	var where = str.indexOf('eng');

	if (where != -1) { 
	  var pre = str.substring(0,where);
	  // alert (pre)
	  var subs  = str.substring(where,where+3);
	  // alert (subs)
	  var post = str.substring(where+3,100);
	  // alert (post)
	  var nuovo = pre + 'ita' + post;
	  //alert (nuovo)
	  top.location.href = nuovo;
	  }
	  else  { 
	  where = str.indexOf('ita');
	  var pre = str.substring(0,where);
	  // alert (pre)
	  var subs  = str.substring(where,where+3);
	  // alert (subs)
	  var post = str.substring(where+3,100);
	  // alert (post)
	  var nuovo = pre + 'eng' + post;
	  //alert (nuovo)
	  top.location.href = nuovo;
	  }
}