Compilare: main.cpp: In member function 'void Trie::insert(std::__cxx11::string)': main.cpp:21:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); i++) ~~^~~~~~~~~~ main.cpp: In member function 'int Trie::count(std::__cxx11::string, int)': main.cpp:37:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i >= s.size() || now -> next[s[i] - 'a'] == nullptr) ~~^~~~~~~~~~~ main.cpp: At global scope: main.cpp:49:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type] main() ^