Compilare: main.cpp: In function 'void convexHull()': main.cpp:62:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < upper_envelope.size(); ++i) ~~^~~~~~~~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:70:42: 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); ^ main.cpp:71:44: 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); ^ main.cpp:74:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &N); ^ main.cpp:78:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%lf%lf", &x, &y); ^