function validate_login (frm) {
  if (frm.username.value.length < 14 ) {
    alert('Enter your username.');
    return false;
  }
  if (frm.password.value.length < 2) {
    alert('Enter your password.');
    return false;
  }
  if (frm.captcha) {
    if (frm.captcha.value.length != 4) {
      alert('Enter the security code shown in the image.');
      return false;
    }
  }
}