Compilare: main.cpp: In function 'int main()': main.cpp:23:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 23 | for (int i = 0; i < s.size(); i++) | ~~^~~~~~~~~~ main.cpp:27:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 27 | for (; j < s.size() && isletter(s[j]); j++) | ~~^~~~~~~~~~