addLoadEvent(didChange);
function addLoadEvent(func) {
    var oldonload = window.onload;
	if (typeof window.onload != 'function') {
		window.onload = func;
	} else {
		window.onload = function() {
			oldonload();
			func();
		}
	}
}

function getType(event) {
	   event = event || window.event;
	   return event.type;
	}
	var change = false;
	function didChange()
	{
	  if (!document.getElementById('personen')) return true;
	  var personen = document.getElementById('personen');
	  var preis = document.getElementById('preis');
	  personen.onchange = personen.onblur = function(event) {
	    var response = document.getElementById('response');
	    if (getType(event) == "change") {
		rechenzahl = eval(personen.value)*(eval(preis.value));
		  if(personen!=0){
   			  response.innerHTML = '<b>'+rechenzahl+',00 waehrung </b>zzgl. MwSt. /VAT'
		      change = true;
			  } else {
			  response.innerHTML = '<b>'+rechenzahl+',00 waehrung </b>zzgl. MwSt. /VAT';
			  change = false;
			  }
	    } else if (!change) {
	      response.innerHTML = '<b>'+rechenzahl+',00 waehrung </b>zzgl. MwSt. /VAT';
	    }
	  }  
	}

function MM_swapImgRestore() { //v3.0
  var i,x,a=document.MM_sr; for(i=0;a&&i<a.length&&(x=a[i])&&x.oSrc;i++) x.src=x.oSrc;
}

function MM_preloadImages() { //v3.0
  var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
    var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
    if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
}

function MM_findObj(n, d) { //v4.0
  var p,i,x;  if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
    d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
  if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
  for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document);
  if(!x && document.getElementById) x=document.getElementById(n); return x;
}

function MM_swapImage() { //v3.0
  var i,j=0,x,a=MM_swapImage.arguments; document.MM_sr=new Array; for(i=0;i<(a.length-2);i+=3)
   if ((x=MM_findObj(a[i]))!=null){document.MM_sr[j++]=x; if(!x.oSrc) x.oSrc=x.src; x.src=a[i+2];}
}