Compilare: main.cpp: In member function 'virtual void Trie::add(std::__cxx11::string)': main.cpp:33:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < word.length(); i++) { ~~^~~~~~~~~~~~~~~ main.cpp: In member function 'virtual void Trie::remove(std::__cxx11::string)': main.cpp:51:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < word.length(); i++) { ~~^~~~~~~~~~~~~~~ main.cpp: In member function 'virtual int Trie::occurences(std::__cxx11::string)': main.cpp:88:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < word.length(); i++) { ~~^~~~~~~~~~~~~~~ main.cpp: In member function 'virtual int Trie::longestPrefixLength(std::__cxx11::string)': main.cpp:106:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < word.length(); i++) { ~~^~~~~~~~~~~~~~~