Compilare: user.cpp: In function ‘int main()’: user.cpp:2:102: 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);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",x);} ^ user.cpp:2:133: 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);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",x);} ^ user.cpp:2:150: 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);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",x);} ^