How can I get number of unread emails from Gmail?

private void button1_Click(object sender, EventArgs e)
{
    TcpClient mail = new TcpClient();
    SslStream sslStream;
    int bytes = -1;
    Cursor = Cursors.WaitCursor;


    mail.Connect("pop.gmail.com", 995);
    sslStream = new SslStream(mail.GetStream());

    sslStream.AuthenticateAsClient("pop.gmail.com");
    Cursor = Cursors.Default;
    byte[] buffer = new byte[2048];

    // Read the stream to make sure we are connected
    bytes = sslStream.Read(buffer, 0, buffer.Length);

    sslStream.Write(Encoding.ASCII.GetBytes("USER USER_EMAIL"+ "\r\n"));
    sslStream.Flush();
    bytes = sslStream.Read(buffer, 0, buffer.Length);
    listBox1.Items.Add(Encoding.ASCII.GetString(buffer, 0, bytes));

    sslStream.Write(Encoding.ASCII.GetBytes("PASS USER_PASSWORD" + "\r\n"));
    sslStream.Flush();
    bytes = sslStream.Read(buffer, 0, buffer.Length);
    listBox1.Items.Add(Encoding.ASCII.GetString(buffer, 0, bytes));

    sslStream.Write(Encoding.ASCII.GetBytes("STAT\r\n"));
    sslStream.Flush();
    bytes = sslStream.Read(buffer, 0, buffer.Length);
    listBox1.Items.Add(Encoding.ASCII.GetString(buffer, 0, bytes));

    sslStream.Write(Encoding.ASCII.GetBytes("RETR 1\r\n"));
    bytes = sslStream.Read(buffer, 0, buffer.Length);
    listBox1.Items.Add(Encoding.ASCII.GetString(buffer, 0, bytes));
    mail.Close();
}