function format_currency(price, seperator)
{
    var cents = Math.floor(price % 100);
    var rest = Math.floor(price / 100);
    if (cents<10)
        return rest+seperator+'0'+cents;
    else
        return rest+seperator+cents;
}

function display_el(el, price)
{
    if (!isNaN(el.value) && (el.value != '') && (el.value > 0))
    {
        var aprice = Math.round((price*parseInt(el.value))*100)/100;
        document.getElementById(el.id+'_display').innerHTML = format_currency(aprice*100, ',')+' €';
        asum += aprice;
    }
    else
    {
        document.getElementById(el.id+'_display').innerHTML = '-';
    }
}
function calc()
{
    asum = 0;
    display_el(document.getElementById('count_download'), 14.99);
    display_el(document.getElementById('count_cd'), 20.00);
    display_el(document.getElementById('count_familydl'), 25.00);
    display_el(document.getElementById('count_familycd'), 30.00);
    document.getElementById('sum').innerHTML=format_currency(asum*100, ',')+' €';
}

function add(el)
{
if (isNaN(el.value) || (el.value==''))
{
    el.value = '1';
}
else
{
        el.value = parseInt(el.value)+1;
}
    calc();
}

function del(el)
{
if (isNaN(el.value) || (el.value=='') || (el.value < 1))
{
    el.value = '0';
}
else
{
        el.value = parseInt(el.value)-1;
}
    calc();
}