Compilare: user.cpp: In member function ‘void Trie::_Add(std::__cxx11::string)’: user.cpp:34:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < word.size(); ++i){ ~~^~~~~~~~~~~~~ user.cpp: In member function ‘void Trie::_Delete(std::__cxx11::string)’: user.cpp:50:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < word.size(); ++i){ ~~^~~~~~~~~~~~~ user.cpp: In member function ‘int Trie::_GetCount(std::__cxx11::string)’: user.cpp:58:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < word.size(); ++i){ ~~^~~~~~~~~~~~~ user.cpp: In member function ‘int Trie::_LongestPrefix(std::__cxx11::string)’: user.cpp:69:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < word.size(); ++i){ ~~^~~~~~~~~~~~~