Compilare: user.cpp: In function ‘int main()’: user.cpp:21:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bal.in", "r", stdin); ^ user.cpp:22:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bal.out", "w", stdout); ^ user.cpp:25:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &M); ^ user.cpp:30:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^ user.cpp:108:38: warning: ‘pnode’ may be used uninitialized in this function [-Wmaybe-uninitialized] for (const int p: G[pnode]) ^ user.cpp:80:39: warning: ‘pnode’ may be used uninitialized in this function [-Wmaybe-uninitialized] for (const int p: G1[pnode]) ^