Compilare: main.cpp: In function 'void Eval(std::__cxx11::string)': main.cpp:17:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (ind < ch.size()) { ~~~~^~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:67:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < ans.size(); ++ i ) { ~~^~~~~~~~~~~~