#include <algorithm>
#include <iostream>
#include <vector>
 
int main() {
    std::vector<std::string> vc { "ala", "bala", "test", "sample" };
    std::vector<std::string> v2 { "test", "bala" };
 
    std::sort(vc.begin(), vc.end());
    std::sort(v2.begin(), v2.end());
 
    std::vector<std::string> res;
    std::set_difference(vc.begin(), vc.end(),
                        v2.begin(), v2.end(), 
                        std::back_inserter(res));
 
    for (const auto& s: res) {
        std::cout << s << std::endl;
    }
}

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