Compilare: user.cpp: In function ‘void read()’: user.cpp:13:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trafic.in","r",stdin); ^ user.cpp:14:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&n,&m,&g); ^ user.cpp:20:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&x,&y,&d); ^ user.cpp: In function ‘void solve()’: user.cpp:142:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trafic.out","w",stdout); ^ user.cpp: In function ‘int BFS()’: user.cpp:30:14: warning: ‘i’ is used uninitialized in this function [-Wuninitialized] Pre[i]=-1; ^