function cek() {
    $nama = $this->input->post('nama');
    $email = $this->input->post('email');

    if (empty($nama)) {
        $this->session->set_flashdata('notif','<p style="color:red;"><b>Mohon isi nama anda</b></p>');

        redirect('captcha');
    }

    if (empty($email)) {
        $this->session->set_flashdata('notif','<p style="color:red;"><b>Mohon isi email anda</b></p>');

        redirect('captcha');
    }

    echo "
        <script>
            alert('Terima kasih, data anda telah diterima.');
            window.location='".base_url()."';
        </script>
    ";
}