vector<int> missingNumbers(vector<int> arr, vector<int> brr) {
    set<int> s;

    sort(arr.begin(), arr.end());
    sort(brr.begin(), brr.end());

    set_difference(brr.cbegin(),brr.cend(), arr.cbegin(),arr.cend(), inserter(s, s.begin()));
    
    return vector<int>(s.cbegin(), s.cend());
}