timer countdown in asp.net

Label4.Text = "00";
Label5.Text = "02";
Label6.Text = "00";

        if (Label6.Text == "00" || Label6.Text == "0")
        {
            if (Label5.Text == "00" || Label5.Text == "0")
            {
                if (Label4.Text == "00" || Label4.Text == "0")
                {
                    Timer1.Enabled = false;
                }
                else
                {
                    Label4.Text = (Convert.ToInt32(Label4.Text) - 1).ToString();
                    if (Label4.Text.Trim().Length == 1)
                        Label4.Text = "0" + Label4.Text;
                    Label5.Text = "60";
                }
            }
            else
            {
                Label5.Text = (Convert.ToInt32(Label5.Text) - 1).ToString();
                if (Label5.Text.Trim().Length == 1)
                    Label5.Text = "0" + Label5.Text;
                Label6.Text = "60";
            }
        }
        else
        {
            Label6.Text = (Convert.ToInt32(Label6.Text) - 1).ToString();
            if (Label6.Text.Trim().Length == 1)
                Label6.Text = "0" + Label6.Text;
        }