Compilare: user.cpp: In function ‘int main()’: user.cpp:23:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(;v[i].first<=dr && i<v.size(); ++i) ^ user.cpp:9:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dunarea.in","r",stdin); ^ user.cpp:10:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dunarea.out","w",stdout); ^ user.cpp:12:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&a,&b,&n); ^ user.cpp:14:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&x,&y); ^