function Prepocitej(id)
{
  cena=document.getElementById('variantPrices' + id).value;
  cenaId=document.getElementById('variant' + id);
  nasobek=document.getElementById('variant2Prices' + id).value;
  nasobekId=document.getElementById('variant2' + id).value;
  cena=cena.split('#');
  nasobek=nasobek.split('#');
  obsiti=document.getElementById('obsiti' + id);
  stuzka=document.getElementById('stuzka' + id);
  if (cenaId.tagName=='INPUT')
  {
    vyska=cenaId.value;
    cenaId=1;
  }
  else
  {
    vyska=cenaId.options[cenaId.selectedIndex].text;
    cenaId=cenaId.value;
  }
  vyska=vyska.split(' ');
  vyska=vyska[1] / 100;
  var celkem=cena[cenaId] * 100 * nasobek[nasobekId] / 100; //js blbe nasobi?
  document.getElementById('cena' + id).innerHTML= cena[cenaId] + " * " + nasobek[nasobekId] + " = " + (celkem) + " Kč<br />";
  if (obsiti.checked)
  {
    celkem += 20 * 2 * vyska;
    document.getElementById('cenaObsiti' + id).innerHTML= "20 x 2 x " + vyska + " = " + (20 * 2 * vyska) + " Kč<br />";
  }
  else
    document.getElementById('cenaObsiti' + id).innerHTML="";
  document.getElementById('cenaCelkem' + id).innerHTML = celkem + " Kč";
}