/************************************/
    /************   PART 1   ************/
    /************************************/

    // Define variables
    string line;
    int counter = 0;
    int pos = 0;
    double average = 0;
    ifstream num_file("numbers.dat");
    bool active = true;

    // Open file and get line of numbers
    if (num_file.is_open()) {
        getline(num_file, line);
        num_file.close();
    }

    // Get the first number and update position
    counter = stoi( line.substr( 0, 1 ) );
    pos = line.find(" ") + 1;

    // Main loop (for each group)
    while (active) {
        // Secondary loop (for marks in each group)
        for (int i = counter; i > 0; i--) {
            average += stoi(line.substr(pos, 2));
            if (line.find(" ", pos) != -1)
                pos = line.find(" ", pos) + 1;
        }

        // Calculate and display average
        average /= counter;
        cout << "For this group of " << counter << " marks, the average is: " << average << endl;

        // Check if at the end
        if (line.find(" ", pos) != -1) {
            counter = stoi(line.substr(pos, 1));
            pos = line.find(" ", pos) + 1;
        }
        // If finished, end loop
        else {
            active = false;
        }
        // Need to clear the average after each group
        average = 0;
    }