Compilare: main.cpp: In function 'std::string solve(std::string)': main.cpp:11:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 11 | for (int i = 0; i < s.size(); i++) { | ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:54:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 54 | for (int i = 0; i < s.size(); i++) { | ~~^~~~~~~~~~