function checkNumeric(string) {
	var Letters = "1234567890.";
	var i;
	var c;
	for(i = 0; i < string.length; i ++){
		c = string.charAt(i);
		if (Letters.indexOf(c) ==-1) {
			return true;
		}
	}
	return false;
}

function round(num,n) {
	var dd=1;
	var tempnum;
	for(i=0;i<n;i++) {
		dd*=10;
	}
	tempnum = num*dd;
	tempnum = Math.round(tempnum);
	return tempnum/dd;
}

function checkBoxPrice(URL, V) {
	var p = document.getElementById('price');
	var l_price = document.getElementById('l_price');
	var r_price = document.getElementById('r_price');
	if(l_price.value == '' || r_price.value == '' || checkNumeric(l_price.value) || checkNumeric(r_price.value)) {
		alert("Plese type numeric!");
		return false;
	}
	l = round(l_price.value / V, 2);
	r = round(r_price.value / V, 2);
	if(l >= r) {
		alert("The second price must bigger than the first one!");
		return false;
	}
	window.location.href = URL + '&price=' + l + "_" + r;
}