Compilare: main.cpp: In function 'int main()': main.cpp:30:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 30 | for (int i=0; i<s.size(); ++i) { | ~^~~~~~~~~ main.cpp:33:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 33 | while (i<s.size() && isdigit(s[i])) x = x*10+(s[i++]-'0'); | ~^~~~~~~~~