var reg_email = /^(.+)\@(.+)\.(.+)$/

	function sprawdz_formularz() {
	
		f = document.forms['wycena'];

		if (!f.elements['imie'].value.length) {
			alert("Please enter your surname!");
			return false;
		}
		
		if (!f.elements['nazwisko'].value.length) {
			alert("Please enter your name!");
			return false;
		}
		
		if (!f.elements['telefon'].value.length) {
			alert("Please enter your phone number!");
			return false;
		}

		if (!f.elements['email'].value.length) {
			alert("Please enter your e-mail address!");
			return false;
		}
		
		if (f.elements['z_jezyka'].value == f.elements['na_jezyk'].value) {
			alert("You have to choose different languages!");
			return false;
		}
 		
		if (f.elements['email'].value.search(reg_email) == -1) {
			alert('Invalid e-mail address!');
			return false;
		}

		return true;
	}