Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:26:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < Son[x].size(); i++) { ^ user.cpp: In function ‘int main()’: user.cpp:117:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(FILEIN, "r", stdin); ^ user.cpp:118:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(FILEOUT, "w", stdout); ^