Compilare: user.cpp: In function ‘int main()’: user.cpp:23:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=1;i<V.size();++i){ ^ user.cpp:10:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("difprim.in","r",stdin); ^ 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("difprim.out","w",stdout); ^ user.cpp:13:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&l,&r); ^