int maxMin(int k, vector<int> arr) {
    std::sort(arr.begin(), arr.end());
    int min, max, dif;
    dif = arr[arr.size() - 1] - arr[0];
    for (int i = 0; i <= arr.size() - k; i++) {
        min = arr[i];
        max = arr [i + k - 1];
        if (max - min <= dif) {
            dif = max - min;
        }
    }
    return dif;
}