Compilare: main.cpp: In function 'void add_in_trie(Trie*, int)': main.cpp:17:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (index == nw.size()) { ~~~~~~^~~~~~~~~~~~ main.cpp: In function 'void erase_from_trie(Trie*&, int)': main.cpp:29:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (index == nw.size()) { ~~~~~~^~~~~~~~~~~~ main.cpp: In function 'int aparitii(Trie*, int)': main.cpp:40:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (index == nw.size()) { ~~~~~~^~~~~~~~~~~~ main.cpp: In function 'int prefix(Trie*, int)': main.cpp:50:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (index == nw.size()) { ~~~~~~^~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:60:41: 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:61:43: 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) ; ^