Compilare: user.cpp: In function ‘int main()’: user.cpp:50:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<=ans.size()-1;i++) ^ user.cpp:53:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i<ans.size()-1 && ans[i].p==ans[i+1].p) ^ user.cpp:21:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("numar.in","r",stdin); ^ user.cpp:22:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("numar.out","w",stdout); ^ user.cpp:24:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&N); ^