Compilare: user.cpp: In function ‘std::vector<int> eratostene(int)’: user.cpp:27:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 2; i < v.size(); i += 2) ~~^~~~~~~~~~ user.cpp:30:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 2; i < v.size(); ++i) ~~^~~~~~~~~~ user.cpp:34:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = i * i; j < v.size(); j += i) ~~^~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:58:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < posibilitati.size(); ++j) { ~~^~~~~~~~~~~~~~~~~~~~~