Compilare: user.cpp: In function ‘void Read()’: user.cpp:21: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘double GetArea(std::vector<std::pair<double, double>, std::allocator<std::pair<double, double> > >)’: user.cpp:121: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void Print()’: user.cpp:152: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result