Compilare: main.cpp: In function 'int main()': main.cpp:30:22: 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:29:18: warning: unused variable 'ul' [-Wunused-variable] 29 | int nr=0,ul=1; | ^~