Eroare de compilare: user.cpp: In function ‘void add(Trie*, int, std::string&)’: user.cpp:16: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int find(Trie*, int, std::string&)’: user.cpp:29: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘bool remove(Trie*, int, std::string&)’: user.cpp:39: warning: comparison between signed and unsigned integer expressions user.cpp:51: error: ‘head’ was not declared in this scope user.cpp: In function ‘int prefix(Trie*, int, std::string&)’: user.cpp:59: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:71: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:72: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:77: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result