function getCheckForm() {
	var dc = document.forms['f1'].elements['f_n'];
	var eX = /^[0-9a-zA-Z]+$/;
	if (!dc.value.match(eX) || dc.value.length < 4) {
		dc.focus();
		alert('Please fill in your username first.');
		return false;
	}
	else {
		return true;
	}
}