Compilare: user.cpp: In function ‘int main()’: user.cpp:29:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] {for (j=0;j<V[i].size();j++) ^ user.cpp:11:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("3color.in","r",stdin); ^ 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("3color.out","w",stdout); ^ user.cpp:13:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&v,&e); ^ user.cpp:16:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^