Compilare: main.cpp: In function 'bool check(std::string)': main.cpp:13:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 13 | for (int i = 0; i < aux.size(); i++) | ~~^~~~~~~~~~~~ main.cpp: In function 'std::string solve()': main.cpp:48:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 48 | for (int i = 0; i < s.size() - 1; ++i) | ~~^~~~~~~~~~~~~~