Compilare: user.cpp: In function ‘void addWord(int, std::string&, Trie*)’: user.cpp:26:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (index == w.size() - 1) ^ user.cpp: In function ‘void deleteWord(int, std::string&, Trie*)’: user.cpp:37:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (index == w.size() - 1) ^ user.cpp: In function ‘int countWord(int, std::string&, Trie*)’: user.cpp:56:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (index == w.size() - 1) ^ user.cpp: In function ‘int longestPrefix(int, int, std::string&, Trie*)’: user.cpp:69:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (index != w.size() - 1 && t->prefixes >= 1) ^