Compilare: main.cpp: In function 'int main()': main.cpp:15:26: 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 k=0;k<s.size();k++){ | ~^~~~~~~~~ main.cpp:20:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 20 | for(int i=0;i<s.size();i++){ | ~^~~~~~~~~