Compilare: main.cpp: In member function 'void Trie::insert(std::__cxx11::string&)': main.cpp:23:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(short i = 0; i < s.size(); ++i) { ~~^~~~~~~~~~ main.cpp:25:27: warning: array subscript has type 'char' [-Wchar-subscripts] if(curr->nxt[c] == 0) { ^ main.cpp:26:28: warning: array subscript has type 'char' [-Wchar-subscripts] curr->nxt[c] = new Node(); ^ main.cpp:28:31: warning: array subscript has type 'char' [-Wchar-subscripts] curr = curr->nxt[c]; ^ main.cpp: In member function 'void Trie::count(std::__cxx11::string&, int, int)': main.cpp:40:27: warning: array subscript has type 'char' [-Wchar-subscripts] if(curr->nxt[c] != 0 && i <= j) { ^ main.cpp:42:35: warning: array subscript has type 'char' [-Wchar-subscripts] curr = curr->nxt[c]; ^ main.cpp: In function 'int main()': main.cpp:73:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < S.size(); ++i) { ~~^~~~~~~~~~