void AppendAdaBoostClassifier(const AdaBoostClassifier& ada)
{
    CascadeClassifier cas;
    ifstream f;
    ofstream of;

    f.open(cascade_filename);
    cas.ReadFromFile(f);
    f.close();

    cas.ac[cas.count] = ada;
    cas.count++;

    of.open(cascade_filename);
    cas.WriteToFile(of);
    of.close();
}