var price = 0 ;
    var fworkSet = 0;
    var dieselSet = 0;
    var sdbSet = 0;
    var makostSet = 0;
    var wkrtierSet = 0;
    var baukostSet = 0;
    var greenhouseSet = 0;
    
    // change me if necessary
    var stdPrice = 15;

    function add(x, y)
    {
        var checked = document.getElementById(y).checked;
        
        // debugging
        // alert("add(x, y)");

        if (y == "feldarbeit")
        {

            if (checked && fworkSet == 0)
            {
                price = price + x
                fworkSet = 1
            }

            if (!checked && fworkSet == 1) {
                price = price - x
                fworkSet = 0;
            }
        }
        if (y == "diesel")
        {
            if (checked && dieselSet == 0)
            {
                price = price + x
                dieselSet = 1
            }

            if (!checked && dieselSet == 1) {
                price = price - x
                dieselSet = 0
            }
        }
        if (y == "standard")
        {
            if (checked && sdbSet == 0)
            {
                price = price + x
                sdbSet = 1
            }

            if (!checked && sdbSet == 1) {
                price = price - x
                sdbSet = 0
            }
        }

         if (y == "makost")
        {
            if (checked && makostSet == 0)
            {
                price = price + x
                makostSet = 1
            }

            if (!checked && makostSet == 1) {
                price = price - x
                makostSet = 0
            }
        }
            if (y == "wkrtier")
        {
            if (checked && wkrtierSet == 0)
            {
                price = price + x
                wkrtierSet = 1
            }

            if (!checked && wkrtierSet == 1) {
                price = price - x
                wkrtierSet = 0
            }
        }
            if (y == "baukost")
        {
            if (checked && baukostSet == 0)
            {
                price = price + x
                baukostSet = 1
            }

            if (!checked && baukostSet == 1) {
                price = price - x
                baukostSet = 0
            }
        }
            if (y == "greenhouse")
        {
            if (checked && greenhouseSet == 0)
            {
                price = price + x
                greenhouseSet = 1
            }

            if (!checked && greenhouseSet == 1) {
                price = price - x
                greenhouseSet = 0
            }
        }
        document.getElementById("sum").innerHTML = price + " €"
        var value = document.createAttribute("value");
        value.nodeValue = price;
        var Element = document.getElementById("eingabe").endSum
        Element.setAttributeNode(value);

    }
    
    function resetSum()
    {
    	
    	// alert("resetSum()");
    	price = 0
    	fworkSet = 0
    	dieselSet = 0
    	sdbSet = 0
    	makostSet = 0
    	wkrtierSet = 0
    	baukostSet = 0
    	greenhouseSet = 0
    	
    	document.getElementById("sum").innerHTML = price + " €"
        var value = document.createAttribute("value");
        value.nodeValue = price;
        var Element = document.getElementById("eingabe").endSum
        Element.setAttributeNode(value);
    	 
    }
    
    function loaded(){
    	
    	// alert("loaded()");
    	
    	// on error, make right price
    	var feldarbeit = document.getElementById("feldarbeit").checked;
    	// alert("feldarbeit : " + document.getElementById("feldarbeit"));
    	
    	var diesel = document.getElementById("diesel").checked;
    	// alert("diesel : " + document.getElementById("diesel"));
    	
    	var standard = document.getElementById("standard").checked;
    	// alert("standard : " + document.getElementById("standard"));
    	
    	var makost = document.getElementById("makost").checked;
    	// alert("makost : " + document.getElementById("makost"));
    	
    	var wkrtier = document.getElementById("wkrtier").checked;
    	// alert("wkrtier : " + document.getElementById("wkrtier"));
    	
    	var baukost = document.getElementById("baukost").checked;
    	// alert("baukost : " + document.getElementById("baukost"));
    	
    	var greenhouse = document.getElementById("greenhouse").checked;
    	// alert("greenhouse : " + document.getElementById("greenhouse"));
    	
    	if(feldarbeit){
    		price = price + stdPrice
    		fworkSet = 1
    	} 
    	
    	if(diesel){
    		
    		// alert("diesel -> true");
    		price = price + stdPrice
    		dieselSet = 1
    	}
    	
    	
    	if(standard){
    		price = price + stdPrice
    		sdbSet = 1
    	}
  
    	if(makost){
    		
    		// alert("makost -> true");
    		price = price + stdPrice
    		makostSet = 1
    	}
    	
    	if(wkrtier){
    		price = price + stdPrice
    		wkrtierSet = 1
    	}
    	
    	if(baukost){
    		price = price + stdPrice
    		baukostSet = 1
    	}
    	
    	
    	if(greenhouse){
    		price = price + stdPrice
    		greenhouseSet = 1
    	}
    	
    	
    	// alert("price : " + price);
    	
    	document.getElementById("sum").innerHTML = price + " €"
        var value = document.createAttribute("value");
        value.nodeValue = price;
        var Element = document.getElementById("eingabe").endSum
        Element.setAttributeNode(value);
    	
    }