string arrToStr(vector<int>& arr) {
    stringstream ss;
    for (int num : arr) {
        ss << num << " ";
    }
    return ss.str();
}

vector<int> strToArr(string& str) {
    vector<int> arr;
    stringstream ss(str);
    int num;
    while (ss >> num) {
        arr.push_back(num);
    }
    return arr;
}