Compilare: user.cpp: In function ‘int val_max(int, std::vector<std::pair<int, int>, std::allocator<std::pair<int, int> > >&)’: user.cpp:21: warning: comparison between signed and unsigned integer expressions user.cpp:24: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:44: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:45: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result