Compilare: main.cpp: In function 'void Add(std::__cxx11::string)': main.cpp:31:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); i++) ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.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); ^ main.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); ^