Compilare: user.cpp: In function ‘int main()’: user.cpp:8:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("divprim.in","r",stdin); ^ user.cpp:9:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("divprim.out","w",stdout); ^ user.cpp:11:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d",&t); ^ user.cpp:28:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d",&n,&k); ^ user.cpp:22:20: warning: iteration 100004u invokes undefined behavior [-Waggressive-loop-optimizations] if (c[j]==i) ^ user.cpp:21:9: note: containing loop for (j=1;j<=1000000;j++) ^ user.cpp:15:16: warning: iteration 50001u invokes undefined behavior [-Waggressive-loop-optimizations] if (c[i]==0) ^ user.cpp:14:5: note: containing loop for (i=3;i<=1000000;i+=2) ^ user.cpp:13:15: warning: iteration 50002u invokes undefined behavior [-Waggressive-loop-optimizations] c[i]=1; ^ user.cpp:12:5: note: containing loop for (i=2;i<=1000000;i+=2) ^