#include <algorithm>
#include <numeric>
#include <iterator>
#include <vector>
#include <fstream>
#include <iostream>
#include <set>

std::set<std::string> find_all(std::set<std::string> const& a,
                               std::set<std::string> const& b)
{
    std::set<std::string> result { };
    std::set_union(
        std::begin(a), std::end(a),
        std::begin(b), std::end(b),
        std::inserter(result, std::begin(result)));
    return result;
}

std::set<std::string> read_team(std::istream& is)
{
    std::set<std::string> result { };

    std::size_t n { };
    is >> n;

    std::copy_n(std::istream_iterator<std::string>{ is }, n,
                std::inserter(result, std::end(result)));

    return result;
}

int main()
{
    std::ifstream ifs { "teams.txt" };

    std::size_t m { };
    ifs >> m;

    std::vector<std::set<std::string>> teams { };
    std::generate_n(std::back_inserter(teams), m,
                    [&ifs]() { return read_team(ifs); });

    std::set<std::string> employees {
        std::accumulate(std::begin(teams), std::end(teams),
                        std::set<std::string>{ },
                        find_all)
    };

    std::cout << "All employees are:" << std::endl;
    std::copy(std::begin(employees), std::end(employees),
              std::ostream_iterator<std::string>{ std::cout, "\n" });

    auto it = std::max_element(std::begin(teams), std::end(teams),
                               [](auto&& a, auto&& b)
                               { return a.size() < b.size(); });

    std::cout << "The largest team consists of:" << std::endl;
    std::copy(std::begin(*it), std::end(*it),
              std::ostream_iterator<std::string>{ std::cout, "\n" });
}