Compilare: user.cpp: In function ‘int main()’: user.cpp:22:14: warning: statement has no effect [-Wunused-value] for(d;d*d<=x;d+=2){ ^ user.cpp:8:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("exp1.in","r",stdin); ^ user.cpp:9:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("exp1.out","w",stdout); ^ user.cpp:11:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n%d\n",&m, &n); ^ user.cpp:13:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&x); ^ user.cpp:39:19: warning: iteration 29999u invokes undefined behavior [-Waggressive-loop-optimizations] if(a[i]) ^ user.cpp:38:9: note: containing loop for(int i=2;i<=30003;i++){ ^