Compilare: main.cpp: In member function 'void Trie::insert(std::__cxx11::string&)': main.cpp:32:26: 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:90:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); ++i) { ~~^~~~~~~~~~