function validEmail(email) {
	var filter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
	return filter.test(email);
}

function fly(id, stat) {
	if(document.getElementById) {
		if(stat) {
			document.getElementById(id).style.visibility = 'visible';	
		}
		else {
			document.getElementById(id).style.visibility = 'hidden';	
		}
	}
}

function checkQuant(f) {
	if(f.quantity.value>0) {
		return true;	
	}
	return false;
}