Compilare: user.cpp: In function ‘int main()’: user.cpp:39:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ciclueuler.in", "r", stdin); ^ user.cpp:40:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ciclueuler.out", "w", stdout); ^ user.cpp:43:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &M); ^ user.cpp:46:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &muc[i].u, &muc[i].v); ^ user.cpp:48:32: warning: ‘u’ may be used uninitialized in this function [-Wmaybe-uninitialized] muchii[u].push_back(&muc[i]); ^ user.cpp:49:32: warning: ‘v’ may be used uninitialized in this function [-Wmaybe-uninitialized] muchii[v].push_back(&muc[i]); ^