Compilare: user.cpp: In function ‘void getHull(std::vector<Line>&)’: user.cpp:67:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < lines.size(); ++ i) { ^ user.cpp: In function ‘int main()’: user.cpp:110:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("copacsmenar.in", "r", stdin); ^ user.cpp:111:44: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("copacsmenar.out", "w", stdout); ^