void readFile (int index, list<studentas> &s) {

    string line;
    studentas soi;
    int allMarks;
    string x = "studentai";
    string xB = "studentai";
    string y = ".txt";
    for (int i = 1; i <= 5; i++) {
        x.append(to_string(i));
        x.append(y);
        ifstream file_(x);

        getline(file_, line); //pirmas

        while (getline(file_, line)) {
            istringstream pirmi(line);

            pirmi >> soi.firstName;
            pirmi >> soi.secondName;
            pirmi >> soi.allMarks;

            index++;
        }
        x = xB;

        s.push_back(studentas());
        studentas *sPtr = &s.back();
        (*sPtr).firstName = soi.firstName;
        (*sPtr).firstName = soi.secondName;
        (*sPtr).allMarks = soi.allMarks;
        soi = {};
    }
}