Compilare: user.cpp: In function ‘std::vector<int> product(const std::vector<int>&, const std::vector<int>&)’: user.cpp:44:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (n <= a.size() + b.size()) ^ user.cpp:48:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < a.size(); ++i) ^ user.cpp:51:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < b.size(); ++i) ^ user.cpp: In function ‘void test()’: user.cpp:97:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < res.size(); ++i) ^