function zam_suma() {
	var koszt = 0;
	for (var i = 1; i <= document.getElementById("liczba").value; i++){
		var cena = document.getElementById("cena" + i).value;
		var ilosc = document.getElementById(document.getElementById("ilosc" + i).value);
		if((isNaN(cena) == false) || (isNaN(ilosc) == false))
			koszt = koszt + cena * ilosc;
			koszt = Math.round(koszt * 100) / 100;
		}
	document.getElementById("suma").value = koszt;
}

function suma() {
	var koszt = 0;
	var array = document.getElementsByName("ilosc");
	for (var i = 0; i < array.length; i++){
		var id = array[i].value;
		var cena = document.getElementById("cena" + (i + 1)).value;
		var ilosc = document.getElementById(id).value;
		if((isNaN(cena) == false) || (isNaN(ilosc) == false)) {
			koszt = koszt + cena * ilosc;
			koszt = Math.round(koszt * 100) / 100;
		}
	}
	document.getElementById("suma").value = koszt;
}

function edit_int(elementID){
	var wartosc = document.getElementById(elementID).value;
	if(isNaN(wartosc) || wartosc < 0 || trim(wartosc, " ").length == 0) {
		document.getElementById(elementID).value = 0;
	}
	suma();
}

function trim(str, chars) {
	return ltrim(rtrim(str, chars), chars);
}
 
function ltrim(str, chars) {
	chars = chars || "\\s";
	return str.replace(new RegExp("^[" + chars + "]+", "g"), "");
}
 
function rtrim(str, chars) {
	chars = chars || "\\s";
	return str.replace(new RegExp("[" + chars + "]+$", "g"), "");
}