Compilare: main.cpp: In function 'long long int vef(std::string)': main.cpp:20:30: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 20 | for(int i=(s[0] == '-');i<s.size();++i) | ~^~~~~~~~~ main.cpp: At global scope: main.cpp:59:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type] 59 | main() | ^~~~