Compilare: user.cpp: In function ‘int main()’: user.cpp:19:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("disjoint.in", "r", stdin); ^ user.cpp:20:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("disjoint.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, &K); ^ user.cpp:31:43: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &comm, &arg1, &arg1); ^ user.cpp:12:25: warning: ‘arg2’ may be used uninitialized in this function [-Wmaybe-uninitialized] if(node == father[node]) ^ user.cpp:22:22: note: ‘arg2’ was declared here int i, comm, arg1, arg2; ^