Compilare: user.cpp: In function ‘double convex_hull(std::vector<int, std::allocator<int> >)’: user.cpp:35: warning: comparison between signed and unsigned integer expressions user.cpp:37: warning: comparison between signed and unsigned integer expressions user.cpp:50: warning: comparison between signed and unsigned integer expressions user.cpp:53: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:106: warning: comparison between signed and unsigned integer expressions user.cpp:107: warning: comparison between signed and unsigned integer expressions user.cpp:65: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:66: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:67: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:74: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result