Compilare: main.cpp: In function 'int parse(std::string)': main.cpp:15:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 15 | for(int i = 0; i < S.size() - 1; ++i) | ~~^~~~~~~~~~~~~~