Compilare: user.cpp: In function ‘int main()’: user.cpp:84:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("mst.in", "r", stdin); ^ user.cpp:85:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("mst.out", "w", stdout); ^ user.cpp:87:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d", &N, &M); ^ user.cpp:89:98: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d %d %d %d", &edge[i].x, &edge[i].y, &edge[i].eq.a, &edge[i].eq.b, &edge[i].eq.c); ^