Compilare: user.cpp: In function ‘int prim(long long int)’: user.cpp:29:24: warning: left operand of comma operator has no effect [-Wunused-value] for (long i=1;i<=pr[0],pr[i]*pr[i]<=x;i++) ^ user.cpp: In function ‘int main()’: user.cpp:78:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ubercool.in","r",stdin); ^ user.cpp:79:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ubercool.out","w",stdout); ^ user.cpp:83:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld\n",&t); ^ user.cpp:85:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld\n",&x); ^