Compilare: user.cpp: In member function ‘void Trie::insert(std::string, int, int)’: user.cpp:23:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (pos == s.size()) { ^ user.cpp: In function ‘void BFS(Trie*)’: user.cpp:41:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (start < Q.size()) { ^ user.cpp: In function ‘int main()’: user.cpp:99:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < result.size(); i++) ^ user.cpp:70:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("virus.in", "r", stdin); ^ user.cpp:71:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("virus.out", "w", stdout); ^ user.cpp:74:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n", &N, &M); ^ user.cpp:75:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s", aux); ^ user.cpp:81:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n%s", &x, aux); ^