Compilare: user.cpp: In function ‘int main()’: user.cpp:2:111: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std; long long n,I,v[1300005]; bool ok[1300005]; int main() { freopen("prim.in","r",stdin); freopen("prim.out","w",stdout); scanf("%lld\n", &n); memset(ok,true,sizeof(ok)); for (int i = 2; i<=1299722; ++i) { if (ok[i]) { v[++I]=i; for (int j = i*2 ; j<=1299722; j+=i) { ok[j]=false; } } } long long x=1LL*v[n+1]*v[n+1]; printf("%lld\n",x); return 0;} ^ user.cpp:2:147: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std; long long n,I,v[1300005]; bool ok[1300005]; int main() { freopen("prim.in","r",stdin); freopen("prim.out","w",stdout); scanf("%lld\n", &n); memset(ok,true,sizeof(ok)); for (int i = 2; i<=1299722; ++i) { if (ok[i]) { v[++I]=i; for (int j = i*2 ; j<=1299722; j+=i) { ok[j]=false; } } } long long x=1LL*v[n+1]*v[n+1]; printf("%lld\n",x); return 0;} ^ user.cpp:2:172: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std; long long n,I,v[1300005]; bool ok[1300005]; int main() { freopen("prim.in","r",stdin); freopen("prim.out","w",stdout); scanf("%lld\n", &n); memset(ok,true,sizeof(ok)); for (int i = 2; i<=1299722; ++i) { if (ok[i]) { v[++I]=i; for (int j = i*2 ; j<=1299722; j+=i) { ok[j]=false; } } } long long x=1LL*v[n+1]*v[n+1]; printf("%lld\n",x); return 0;} ^