Compilare: user.cpp: In function ‘void Add(std::string)’: user.cpp:31:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:87:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("cli.in", "r", stdin); ^ user.cpp:88:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("cli.out", "w", stdout); ^