Compilare: main.cpp: In function 'int main()': main.cpp:30:23: 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:65:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 65 | for (int i = 2; i < s.size(); i += 2) | ~~^~~~~~~~~~