Compilare: user.cpp: In function ‘std::vector<int> product(const std::vector<int>&, const std::vector<int>&)’: user.cpp:65:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (n < 2 * a.size() || n < 2 * b.size()) ^ user.cpp:65:47: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (n < 2 * a.size() || n < 2 * b.size()) ^ user.cpp:69:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < a.size(); ++ i) ^ user.cpp:72:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < b.size(); ++ i) ^ user.cpp: In function ‘int main()’: user.cpp:122:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < C.size(); ++ i) ^