#include <iostream>
#include <iterator>
#include <vector>
#include <algorithm>

int main() {
    std::vector<int> a = {1,2,3,4,5,5};
    std::vector<int> b = {5,5,5,5,4};
    std::vector<int> c;

    std::sort(a.begin(), a.end());
    std::sort(b.begin(), b.end());
    std::set_intersection(a.begin(), a.end(), b.begin(), b.end(), std::back_inserter(c));

    for (auto &x : c) {
        std::cout << x << std::endl;
    }
}