void extraLongFactorials(int n) {
    vector<int> bigInt;
    
    // Extract digits of n to initialise bigInt
    {
        stringstream ss;
        ss << n;
        string nString;
        ss >> nString;
        for (char c : nString)
            bigInt.push_back(c - '0');
        --n;
    }
    
    for (; n > 0; --n)
    {
        // Calculate the product of each individual digit of bigInt with n
        vector<int> product;
        for (unsigned int i = 0; i < bigInt.size(); ++i)
            product.push_back(bigInt[i] * n);
        
        // determine new size of bigInt
        {
            size_t prevSize = bigInt.size();
            stringstream ss;
            ss << n;
            bigInt = vector<int>(prevSize + ss.str().length(), 0);
        }
        
        // Add products to bigInt one by one
        int sizeDiff = static_cast<int>(bigInt.size() - product.size());
        int carryOver = 0;
        for (int j = static_cast<int>(bigInt.size() - 1); j >= 0; --j)
        {
            if (j - sizeDiff < 0)
            {
                if (carryOver > 0)
                {
                    bigInt[j] = carryOver % 10;
                    carryOver /= 10;
                }
                else
                {
                    // pop remaining leading 0s, erase() is [first, last)
                    bigInt.erase(bigInt.begin(), bigInt.begin() + j + 1);
                    break;
                }
            }
            else
            {
                bigInt[j] = (carryOver + product[j - sizeDiff]) % 10;
                carryOver = (carryOver + product[j - sizeDiff]) / 10;
            }
        }
    }
    
    for (int i : bigInt)
        cout << i;
}