function VerificaDati() {
OK=(document.ef.FromDate.selectedIndex>0);
OK=(OK) && (document.ef.number.selectedIndex>0);
OK=(OK) && (document.ef.NumberOfDays.selectedIndex>0);
OK=(OK) && (document.ef.Email.value.match("([a-z|0-9|.]+)@([a-z|0-9]+).([a-z|0-9|.]+)")!=null);
if (!OK) {
alert('Please write the required data');
document.refresh;}}