#include <iostream>
#include <iterator>
#include <vector>
#include <unordered_set>
#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::unordered_set<int> t(a.begin(), a.end());
 
    for (auto &x : b) {
        auto it = t.find(x);
        if (it != t.end()) {
            c.push_back(x);
            t.erase(it);
        }
    }
 
    for (auto &x : c) {
        std::cout << x << std::endl;
    }
}

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