Compilare: user.cpp: In function ‘std::vector<point> hull(std::vector<point>&)’: user.cpp:167:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i < pts.size(); i++) ~~^~~~~~~~~~~~ user.cpp:178:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < pts.size(); i++) { ~~^~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:190:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("infasuratoare.in", "r", stdin); ^ user.cpp:191:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("infasuratoare.out", "w", stdout); ^