void MainWindow::save()
{
    QString filename = QFileDialog::getSaveFileName(this, "Save", "", "Data (*.data)");
    if(!filename.isEmpty()) {
        this->markModel.save(filename.toStdString());
    }
}

void MainWindow::open()
{
    QString filename = QFileDialog::getOpenFileName(this, "Save", "", "Data (*.data)");
    if(!filename.isEmpty()) {
        this->markModel.clear();
        this->markModel.load(filename.toStdString());

        double average = this->markModel.getAverage();
        this->markLabel->setText("Average: " + QString::number(average));
    }
}