Compilare: user.cpp: In function ‘int presolve(int)’: user.cpp:33:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (X>1 && prime.size()>f) ^ user.cpp: In function ‘int main()’: user.cpp:57:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("maxd.in","r",stdin); ^ user.cpp:58:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("maxd.out","w",stdout); ^ user.cpp:60:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&X,&Y); ^