Compilare: user.cpp: In function ‘void solution()’: user.cpp:30:9: warning: unused variable ‘pre’ [-Wunused-variable] bool pre=false; ^ user.cpp: In function ‘void read()’: user.cpp:17:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld %ld ", &n, &m); ^ user.cpp:21:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld %ld %d ",&x ,&y ,&pr); ^ user.cpp: In function ‘int main()’: user.cpp:71:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bellmanford.in","r",stdin); ^ user.cpp:72:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bellmanford.out","w",stdout); ^ user.cpp: In function ‘void solution()’: user.cpp:58:13: warning: ‘mn’ may be used uninitialized in this function [-Wmaybe-uninitialized] if(vac[mn]>n){ ^