Compilare: user.cpp: In function ‘int main()’: user.cpp:2:77: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;int v[1000010];int main(){freopen("emptri.in","r",stdin);freopen("emptri.out","w",stdout);int n;unsigned long long rez=0;scanf("%d",&n);for(int i=1;i<=n;i++)v[i]=i;for(int d=2;d<=n;d+=2)v[d]=v[d]/2;for(int i=3;i<=n;i+=2)if(v[i]==i)for(int d=i;d<=n;d+=i)v[d]=v[d]/i*(i-1);for(int i=1;i<=n;i++)rez+=v[i];printf("%llu\n",2*rez-1);} ^ user.cpp:2:110: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;int v[1000010];int main(){freopen("emptri.in","r",stdin);freopen("emptri.out","w",stdout);int n;unsigned long long rez=0;scanf("%d",&n);for(int i=1;i<=n;i++)v[i]=i;for(int d=2;d<=n;d+=2)v[d]=v[d]/2;for(int i=3;i<=n;i+=2)if(v[i]==i)for(int d=i;d<=n;d+=i)v[d]=v[d]/i*(i-1);for(int i=1;i<=n;i++)rez+=v[i];printf("%llu\n",2*rez-1);} ^ user.cpp:2:156: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;int v[1000010];int main(){freopen("emptri.in","r",stdin);freopen("emptri.out","w",stdout);int n;unsigned long long rez=0;scanf("%d",&n);for(int i=1;i<=n;i++)v[i]=i;for(int d=2;d<=n;d+=2)v[d]=v[d]/2;for(int i=3;i<=n;i+=2)if(v[i]==i)for(int d=i;d<=n;d+=i)v[d]=v[d]/i*(i-1);for(int i=1;i<=n;i++)rez+=v[i];printf("%llu\n",2*rez-1);} ^