Compilare: user.cpp: In function ‘void add(Trie*, std::string, int)’: user.cpp:17: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void remove(Trie*, std::string, int)’: user.cpp:35: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void print(Trie*, std::string, int)’: user.cpp:54: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void max_prefix(Trie*, std::string, int)’: user.cpp:74: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:110: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:111: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result