Compilare: main.cpp: In function 'Trie* add(std::__cxx11::string, int)': main.cpp:22:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); i++) { ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:67:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); i++) { ~~^~~~~~~~~~