Compilare: main.cpp: In function 'bool check(int)': main.cpp:45:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 45 | while(i < a.length()) | ~~^~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:70:35: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 70 | for(int i = a.length() - 1; i < b.length(); i++) | ~~^~~~~~~~~~~~ main.cpp:84:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 84 | for(int i = 0; i < res.size(); i++) | ~~^~~~~~~~~~~~