int d7p1(const string& filename)
{
    ifstream file(filename);
    string line;
    getline(file, line);
    stringstream iss(line);

    vector<int> crabs;
    for (int number; iss >> number;)
    {
        crabs.push_back(number);
        if (iss.peek() == ',')
            iss.ignore();
    }

    std::sort(crabs.begin(), crabs.end());
    int idx;
    if (crabs.size() % 2 == 1)
        idx = crabs[(crabs.size() + 1) / 2];
    else
    {
        int left = crabs[crabs.size() / 2 - 1];
        int right = crabs[crabs.size() / 2];
        idx = (int)((left + right) / 2);
    }

    int fuel = 0;
    for (const auto& crab : crabs)
    {
        fuel += (int)abs(crab - idx);
    }
    return fuel;
}