function f_valida_formulario(form) {
    var error = "";
	if (form.name.value=="") {
	   error = "You must enter the name\n"
	}
	if (form.phone.value=="") {
	   error = error + "You must enter the phone\n";
	}
	if (form.email.value=="") {
	   error = error + "You must enter the mail\n";
	}
    if (error!="") {
	  alert(error);
	  return false;
	}
  }