#include <iostream>
#include <string>
#include <vector>
#include <set>

using namespace std;

template <typename Documents>
ostream& Print (ostream& out, const Documents& documents) {

    bool is_first = true;
    for (const auto& element : documents) {
        if (!is_first) {
            out << ", "s;
        }
        is_first = false;
        out << element;
    }
    return out;
}

template <typename Element>
ostream& operator<<(ostream& out, const vector<Element>& container) {
    Print(out, container);
    return out;
}

template <typename Element>
ostream& operator<<(ostream& out, const set<Element>& container) {
    Print(out, container);
    return out;
}


int main() {
    const set<string> cats = {"Мурка"s, "Белка"s, "Георгий"s, "Рюрик"s};
    cout << cats << endl;
    const vector<int> ages = {10, 5, 2, 12};
    cout << ages << endl;
    return 0;
}