Compilare: main.cpp: In function 'void add_in_trie(std::__cxx11::string, Trie*, int)': main.cpp:16:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (index == nw.size()) { ~~~~~~^~~~~~~~~~~~ main.cpp: In function 'void erase_from_trie(Trie*&, std::__cxx11::string, int)': main.cpp:28:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (index == nw.size()) { ~~~~~~^~~~~~~~~~~~ main.cpp: In function 'int aparitii(std::__cxx11::string, Trie*, int)': main.cpp:39:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (index == nw.size()) { ~~~~~~^~~~~~~~~~~~ main.cpp: In function 'int prefix(std::__cxx11::string, Trie*, int)': main.cpp:49:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (index == nw.size()) { ~~~~~~^~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:59:41: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("trie.in", "r", stdin) ; ^ main.cpp:60:43: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("trie.out", "w", stdout) ; ^