Compilare: user.cpp: In function ‘int main()’: user.cpp:31:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<succ[u].size();++j) ^ user.cpp:12:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sortaret.in","r",stdin); ^ user.cpp:13:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sortaret.out","w",stdout); ^ user.cpp:15:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:18:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&u,&v); ^