Eroare de compilare: user.cpp: In function ‘std::vector<std::pair<double, double>, std::allocator<std::pair<double, double> > > convexHull(std::vector<std::pair<double, double>, std::allocator<std::pair<double, double> > >)’: user.cpp:27: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘double ariePoligon(std::vector<std::pair<double, double>, std::allocator<std::pair<double, double> > >)’: user.cpp:45: warning: comparison between signed and unsigned integer expressions user.cpp:51: error: ‘fabs’ was not declared in this scope user.cpp: In function ‘double solve(int)’: user.cpp:96: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:110: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:111: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:113: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:116: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:118: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result