Compilare: main.cpp: In function 'void add(std::string)': main.cpp:16:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 16 | for (int i = 0; i < x.size(); i++) | ~~^~~~~~~~~~ main.cpp: In function 'bool check(std::string)': main.cpp:37:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 37 | for (int i = 0; i < x.size(); i++) | ~~^~~~~~~~~~ main.cpp:51:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::__cxx11::basic_string<char> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 51 | for (int i = 0; i < h[x.size()].size(); i++) | ~~^~~~~~~~~~~~~~~~~~~~