Compilare: user.cpp: In function ‘void predf(int)’: user.cpp:19:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < A[x].size(); i++) { ^ user.cpp: In function ‘void ancestors(int)’: user.cpp:58:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < A[x].size(); i++) { ^ user.cpp: In function ‘void df(int)’: user.cpp:70:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < A[x].size(); i++) { ^ user.cpp: In function ‘int num_ops(int)’: user.cpp:81:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sorted.size(); i++) { ^ user.cpp: In function ‘void c(int&)’: user.cpp:32:38: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(s, 1, bufsz, stdin); ^ user.cpp:41:38: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(s, 1, bufsz, stdin); ^ user.cpp: In function ‘int main()’: user.cpp:92:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arborest.in", "r", stdin); ^ user.cpp:93:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arborest.out", "w", stdout); ^ user.cpp:95:30: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(s, 1, bufsz, stdin); ^